Plasma endothelin-1 levels in non-insulin dependent diabetes mellitus patients with macrovascular disease

BACKGROUND: Endothelin-1 (ET-1) with its well-known vasoconstrictive and mitogenic action and through its interaction with insulin, blood glucose, and lipids might play an important role in the accelerated atherogenic process in diabetes mellitus. OBJECTIVE: To determine whether ET-1 levels are indicative of macrovascular disease in diabetes mellitus. METHODS: In the present cross-sectional study, plasma ET-1 concentrations were measured in members of three groups. The first group consisted of 20 patients (15 men and five women; aged 56.3 +/- 12.5 years) with non-insulin-dependent diabetes mellitus and coronary artery disease, the second group of 20 patients (16 men and four women, aged 56.9 +/- 11.2 years) with coronary artery disease only, and the third group of 10 healthy subjects who served as controls. ET-1 levels were determined by a radioimmunoassay. RESULTS: The mean plasma ET-1 levels for the three groups were 3.59 +/- 1.88, 4.31 +/- 1.32, and 4.42 +/- 1.01 pmol/l respectively, and there was no statistically significant difference among the groups (P = 0.23). There was also no correlation between the plasma ET-1 concentration and age, sex, body mass index, triglyceride, total cholesterol, high-, low- and very-low density lipoprotein levels, for all groups, and, for the first group, hemoglobin A1c (HbA1c), the duration of diabetes mellitus. CONCLUSION: The plasma ET-1 concentration is not elevated in non-insulin-dependent diabetes mellitus patients with macrovascular disease, which might reflect the fact that its action occurs in a paracrine or an autocrine rather than an endocrine fashion and suggests that ET-1 levels are not necessarily indicative of macrovascular disease in diabetes mellitus.     

KB-R7785, a novel matrix metalloproteinase inhibitor, exerts its antidiabetic effect by inhibiting tumor necrosis factor-alpha production

It has been suggested that tumor necrosis factor-alpha (TNF-alpha) is a key mediator of insulin resistance in non-insulin-dependent diabetes mellitus (NIDDM). TNF-alpha is synthesized as a membrane-bound precursor; this is proteolytically processed to an active form by a matrix metalloproteinase (MMP)-like enzyme. In this study, we have used KKAy mice which show insulin resistance like NIDDM to investigate the effects of KB-R7785, a novel MMP inhibitor, on blood glucose and insulin levels. Subcutaneous administration of KB-R7785 at 100 mg/kg twice daily (i.e., 200 mg/kg/day) for 4 weeks resulted in a significant decrease in plasma glucose levels which was observed after 3 weeks. Oral administration of pioglitazone (20 mg/kg twice daily or 40 mg/kg/day for 4 weeks), an agent known to ameliorate insulin sensitivity, significantly decreased plasma glucose levels during the treatment period. KB-R7785, but not pioglitazone, also significantly decreased plasma insulin levels. Lipopolysaccharide (LPS) increased plasma TNF-alpha levels to a significantly greater degree in KKAy mice than in normal C57BL mice; this was inhibitable in KKAy mice by KB-R7785. In contrast, pioglitazone did not affect the LPS-induced increase in plasma TNF-alpha levels in KKAy mice. These results suggest that KB-R7785 exerts its antidiabetic effect by ameliorating insulin sensitivity through the inhibition of TNF-alpha production.     

Cellular Ca2+ ATPase activity in diabetes mellitus

Basal and maximal Ca2+ ATPase activity was studied in erythrocytes of 29 healthy controls, 15 patients with insulin-dependent diabetes mellitus (IDDM) and 22 patients with non-insulin-dependent diabetes mellitus (NIDDM). Basal and maximal Ca2+ ATPase activity was significantly decreased in insulin-dependent diabetes mellitus (8.4 +/- 0.5 and 22.5 +/- 1.1 pmol/10(6) RBC/min) and non-insulin-dependent diabetes mellitus (7.3 +/- 1.0 and 18.6 +/- 1.8 pmol/10(6) RBC/min) compared to healthy controls (9.3 +/- 1.0 and 24.6 +/- 1.1 pmol/10(6) RBC/min). Maximal Ca2+ ATPase activity showed a significant correlation to systolic blood pressure in both insulin-dependent diabetes mellitus and non-insulin-dependent diabetes mellitus. There was no significant correlation of maximal Ca2+ ATPase activity to fasting serum glucose concentration and to HbA1 levels. Maximal Ca2+ ATPase activity was significantly correlated to creatinine clearance in non-insulin-dependent diabetes mellitus, but not in insulin-dependent diabetes mellitus. It is concluded that a decreased cellular Ca2+ ATPase activity may predispose to the development of hypertension in diabetes mellitus.     

Low serum levels of tumor necrosis factor-alpha in insulin-dependent diabetic children

We measured serum levels of tumor necrosis factor-alpha (TNF-alpha) in 48 children with insulin-dependent diabetes mellitus (IDDM), divided into two groups according to disease duration (group I < 6 months and group II > 3 years): group I 15 patients, aged 2.2-13.7 years, and group II 33 patients, aged 4.5-25.5 years. Thirty-six age- and sex-matched healthy subjects served as controls. TNF-alpha levels were measured by immunoradiometric assay. We found that TNF-alpha levels were lower in all IDDM patients (29.65 +/- 3.83 pg/ml) than in controls (74.74 +/- 10.17 pg/ml) (p < 0.0001), as well as in group I (24.07 +/- 3.65 pg/ml) and group II (32.16 +/- 5.29 pg/ml) as compared to controls (p < 0.001). TNF-alpha levels were significantly lower in patients with antibodies than in those without antibodies and in controls. Similar results were found in longstanding IDDM patients. No correlation was found between serum TNF-alpha and chronologic age, duration of disease, metabolic control, insulin requirement and HLA typing. During a 1-year follow-up study in 12 group I patients no significant variations in TNF-alpha levels were observed. It has been reported that the administration of exogenous TNF suppresses the development of diabetes in nonobese diabetic mice, low producers of endogenous TNF. The results suggest that aberrant TNF-alpha synthesis may contribute to immune dysregulation thus favoring the development of autoimmune diseases.     

The effects of non-insulin-dependent diabetes mellitus on the kinetics of onset of insulin action in hepatic and extrahepatic tissues

The mechanism(s) of insulin resistance in non-insulin-dependent diabetes mellitus remains ill defined. The current studies sought to determine whether non-insulin-dependent diabetes mellitus is associated with (a) a delay in the rate of onset of insulin action, (b) impaired hepatic and extrahepatic kinetic responses to insulin, and (c) an alteration in the contribution of gluconeogenesis to hepatic glucose release. To answer these questions, glucose disappearance, glucose release, and the rate of incorporation of 14CO2 into glucose were measured during 0.5 and 1.0 mU/kg-1 per min-1 insulin infusions while glucose was clamped at approximately 95 mg/dl in diabetic and nondiabetic subjects. The absolute rate of disappearance was lower (P < 0.05) and the rate of increase slower (P < 0.05) in diabetic than nondiabetic subjects during both insulin infusions. In contrast, the rate of suppression of glucose release in response to a change in insulin did not differ in the diabetic and nondiabetic subjects during either the low (slope 30-240 min:0.02 +/- 0.01 vs 0.02 +/- 0.01) or high (0.02 +/- 0.00 vs 0.02 +/- 0.00) insulin infusions. However, the hepatic response to insulin was not entirely normal in the diabetic subjects. Both glucose release and the proportion of systemic glucose being derived from 14CO2 (an index of gluconeogenesis) was inappropriately high for the prevailing insulin concentration in the diabetic subjects. Thus non-insulin-dependent diabetes mellitus slows the rate-limiting step in insulin action in muscle but not liver and alters the relative contribution of gluconeogenesis and glycogenolysis to hepatic glucose release.     

Insulin sensitivity in familial hypercholesterolemia

Insulin resistance is found in association with obesity, non-insulin-dependent diabetes mellitus, and essential hypertension, which are all risk factors for atherosclerotic cardiovascular disease. Furthermore, hyperinsulinemia has been reported in familial combined hyperlipoproteinemia and endogenous hypertriglyceridemia. Finally, relatively high serum triglyceride and low high-density lipoprotein (HDL) cholesterol concentrations invariably accompany hyperinsulinemia. Whether insulin sensitivity is affected by the isolated presence of high levels of serum low-density lipoprotein (LDL) cholesterol has not been clearly established. We studied 13 subjects with heterozygous familial hypercholesterolemia (FHC) and 15 normocholesterolemic subjects selected to be free of any other known cause of insulin resistance. Thus FHC patients and controls had normal body weight and fat distribution, glucose tolerance, blood pressure, and serum triglyceride and HDL cholesterol concentrations, but were completely separated on plasma LDL cholesterol concentrations (6.05 +/- 0.38 v 3.27 +/- 0.15 mmol/L, P < .0001). Fasting plasma levels of glucose, insulin, free fatty acids (FFA), and potassium and fasting rates of net carbohydrate and lipid oxidation were superimposable in the two study groups. During a 2-hour euglycemic (approximately 5 mmol/L) hyperinsulinemic (approximately 340 pmol/L) clamp, whole-body glucose disposal rates averaged 30.4 +/- 2.3 and 31.1 +/- 3.0 mumol.kg-1 x min-1 in FHC and control subjects, respectively (P = 0.88). The ability of exogenous hyperinsulinemia to stimulate carbohydrate oxidation and energy expenditure and suppress lipid oxidation and plasma FFA and potassium levels was equivalent in FHC and control subjects.(ABSTRACT TRUNCATED AT 250 WORDS)     

Reduced tyrosine kinase activity of the insulin receptor in obesity-diabetes. Central role of tumor necrosis factor-alpha

Insulin resistance is an important metabolic abnormality often associated with infections, cancer, obesity, and especially non-insulin-dependent diabetes mellitus (NIDDM). We have previously demonstrated that tumor necrosis factor-alpha produced by adipose tissue is a key mediator of insulin resistance in animal models of obesity-diabetes. However, the mechanism by which TNF-alpha interferes with insulin action is not known. Since a defective insulin receptor (IR) tyrosine kinase activity has been observed in obesity and NIDDM, we measured the IR tyrosine kinase activity in the Zucker (fa/fa) rat model of obesity and insulin resistance after neutralizing TNF-alpha with a soluble TNF receptor (TNFR)-lgG fusion protein. This neutralization resulted in a marked increase in insulin-stimulated autophosphorylation of the IR, as well as phosphorylation of insulin receptor substrate 1 (IRS-1) in muscle and fat tissues of the fa/fa rats, restoring them to near control (lean) levels. In contrast, no significant changes were observed in insulin-stimulated tyrosine phosphorylations of IR and IRS-1 in liver. The physiological significance of the improvements in IR signaling was indicated by a concurrent reduction in plasma glucose, insulin, and free fatty acid levels. These results demonstrate that TNF-alpha participates in obesity-related systemic insulin resistance by inhibiting the IR tyrosine kinase in the two tissues mainly responsible for insulin-stimulated glucose uptake: muscle and fat.     

Severe aplastic anaemia relapsing during a pregnancy; spontaneous remission following termination

IFN-gamma and TNF-alpha plasma levels were measured before and after local treatment in 27 patients. Twenty healthy subjects served as controls. Plasma concentrations of IFN-gamma and TNF-alpha were significantly higher before treatment (178.7 +/- 11.9 pg/ml and 31.9 +/- 11.6 pg/ml, respectively) compared to the control group (139.6 +/- 7.86 pg/ml and 17.1 +/- 7.7 pg/ml, respectively). After treatment IFN-gamma levels were significantly decreased (151.3 +/- 8.3 pg/ml) toward the control group values and TNF-alpha levels were observed even lower than in the controls (11.48 +/- 6.8 pg/ml). No correlations were found between age, duration of psoriasis and plasma levels of cytokines. However, IFN-gamma levels were related, although not significantly, to disease severity (evidenced by the PASI score). The data support the important proinflammatory role of IFN-gamma and TNF-alpha in the clinical manifestation of psoriasis.     

Concanavalin A binding by the hippocampal neurons following brief cerebral ischemia in gerbils

Immunoglobulin (Ig) fractions from the plasma of a group of newly diagnosed insulin-dependent diabetes mellitus (type 1) patients and set of control subjects were assessed for their effects on isolated mouse islet function. It was found that Igs from type 1 patients caused a significant inhibitory effect on insulin secretion when incubated with mouse islets as compared with controls (25.6 +/- 2.9 pg islet-1 h-1 vs 44.7 +/- 7.7 pg islet-1 h-1, P < 0.05). The plasma samples from which the Igs were obtained were then tested for the presence of antibodies to the mouse islet cell surface (ICSA). Four of the nine patients were positive for ICSA, and plasma samples from eight control subjects were all negative. ICSA-positive samples appeared to have the greatest inhibitory effect on insulin secretion when compared with their respective controls (53.3 +/- 7.0 pg insulin islet -1 min-1 vs 30.9 +/- 3.7 pg insulin islet -1 min-1, (P < 0.05). In contrast, it was also found that ICSA-positive Ig fractions had no significant effect on glucose oxidation when co-incubated with mouse islets as compared with the controls (11.3 +/- 2.3 pmol islet-1 h-1 vs 11.2 +/- 2.9 pmol islet-1 h-1). These studies suggest that Igs from newly diagnosed type 1 patients containing ICSA may impair insulin secretion from isolated mouse islets by mechanisms which do not involve the inhibition of B-cell glucose metabolism.     

Defects in insulin secretion and action in women with a history of gestational diabetes

Gestational diabetes mellitus (GDM) is associated with defects in insulin secretion and insulin action, and women with a history of GDM carry a high risk for the development of non-insulin-dependent diabetes mellitus (NIDDM). Assessment of subjects with a history of GDM who are currently normoglycemic should help elucidate some of the underlying defects in insulin secretion or action in the evolution of NIDDM. We have studied 14 women with normal oral glucose tolerance who had a history of GDM. They were compared with a group of control subjects who were matched for both body mass index (BMI) and waist-to-hip ratio (WHR). All subjects underwent tests for the determination of oral glucose tolerance, ultradian oscillations in insulin secretion during a 28-h glucose infusion, insulin secretion in response to intravenous glucose, glucose disappearance after intravenous glucose (Kg), and insulin sensitivity (SI) as measured by the Bergman minimal model method. The BMI in the post-GDM women was similar to that in the control subjects (24.9 +/- 1.2 vs. 25.4 +/- 1.4 kg/m2, respectively), as was the WHR ratio (0.80 +/- 0.01 vs. 0.76 +/- 0.01, respectively). The post-GDM women were slightly older (35.2 +/- 0.9 vs. 32.1 +/- 1.4 years, P = 0.04). The fasting plasma glucose levels were significantly higher in the post-GDM group than in the control group (4.9 +/- 0.1 vs. 4.4 +/- 0.1 mmol/l, respectively, P < 0.001) and remained higher at each of the subsequent determinations during the oral glucose tolerance test, although none had a result indicative of either diabetes or impaired glucose tolerance.(ABSTRACT TRUNCATED AT 250 WORDS)     

Tumor necrosis factor-alpha in sera of obese patients: fall with weight loss

In view of the recent demonstration that obesity in animals and humans is associated with an increase in tumor necrosis factor-alpha (TNFalpha) expression, that this expression falls with weight loss, and that TNFalpha may specifically inhibit insulin action, the possibility that TNFalpha may be a mediator of insulin resistance has been raised. We have undertaken this study to investigate whether serum TNFalpha concentrations are elevated in obese subjects, whether they fall after weight loss, and whether this fall parallels the fall in insulin release after glucose challenge. Obese patients (age range: 25-54, weight mean +/- SD: 96.4 +/- 13.8 kg, body mass index: 35.7 +/- 5.6 kg/m2) were started on a diet program. The mean weight fell to 84.5 +/- 11.3 (P < 0.0001) and body mass index to 31.3 +/- 4.9 (P < 0.0001). Plasma TNFalpha concentrations were markedly elevated in the obese (3.45 +/- 0.16 pg/mL), when compared with controls (0.72 +/- 0.28 pg/mL), and fell significantly (2.63 +/- 1.40 pg/mL) after weight loss (P < 0.02). The magnitude of insulin release after glucose (75 g) challenge (area under the curve) also fell significantly (P < 0.01) after weight loss. The magnitude of weight loss and fall in TNFalpha were related to basal body weight (r = 0.57, P < 0.001) and basal TNFalpha (r = 0.55, P < 0.001) concentrations, respectively, but not to each other or to the glucose-induced insulin release (area under the curve). We conclude that obesity is associated with increased plasma TNFalpha concentrations, which fall with weight loss. Because circulating TNFalpha may mediate insulin resistance in the obese, a fall in TNFalpha concentrations may contribute to the restoration of insulin resistance after weight loss, Thus, TNFalpha may be an important circulating cytokine, which may provide a potentially reversible mechanism for mediating insulin resistance.     

Hyperamylinemia is associated with hyperinsulinemia in the glucose-tolerant, insulin-resistant offspring of two Mexican-American non-insulin-dependent diabetic parents

Several investigations have presented evidence that amylin inhibits insulin secretion and induces insulin resistance both in vitro and in vivo. However, basal and postmeal amylin concentrations proved similar in non-insulin-dependent diabetes mellitus (NIDDM) patients and controls. Since hyperglycemia may alter both amylin and insulin secretion, we examined basal and glucose-stimulated amylin secretion in eight glucose-tolerant, insulin-resistant Mexican-American subjects with both parents affected with NIDDM (offspring) and correlated the findings with the insulin sensitivity data acquired by an insulin clamp. Eight offspring and eight Mexican-Americans without any family history of diabetes (controls) underwent measurement of fat free mass (3H2O dilution method), 180-minutes, 75-g oral glucose tolerance test (OGTT), and 40-mU/m2, 180-minute euglycemic insulin clamp associated with 3H-glucose infusion and indirect calorimetry. Fasting amylin was significantly increased in offspring versus controls (11.5 +/- 1.4 v 7.0 +/- 0.8 pmol/L, P < .05). After glucose ingestion, both total (3,073 +/- 257 v 1,870 +/- 202 pmol.L-1.min-1, P < .01) and incremental (1,075 +/- 170 v 518 +/- 124 pmol.L-1.min-1, P < .05) areas under the curve (AUCs) of amylin concentration were significantly greater in offspring. The amylin to insulin molar ratio was similar in offspring and controls at all time points. Basal and postglucose insulin and C-peptide concentrations were significantly increased in the offspring. No correlation was found between fasting amylin, postglucose amylin AUC or IAUC, and any measured parameter of glucose metabolism during a euglycemic-hyperinsulinemic clamp (total glucose disposal, 7.21 +/- 0.73 v 11.03 +/- 0.54, P < .001; nonoxidative glucose disposal, 3.17 +/- 0.59 v 6.33 +/- 0.56, P < .002; glucose oxidation, 4.05 +/- 0.46 v 4.71 +/- 0.21, P = NS; hepatic glucose production, 0.29 +/- 0.16 v 0.01 +/- 0.11, P = NS; all mg.min-1.kg-1 fat-free mass, offspring v controls). In conclusion, these data do not support a causal role for amylin in the genesis of insulin resistance in NIDDM.     

How good a marker is insulin level for insulin resistance?

Epidemiologic studies have correlated fasting and postload insulin levels with the risk of coronary heart disease, assuming that insulin levels are reliable markers of insulin resistance. However, this assumption has not been systematically studied. The author measured insulin response to an oral glucose load and quantitated insulin resistance using the euglycemic hyperinsulinemic clamp technique to evaluate the correlation between insulin level and the degree of insulin resistance in individuals with varying degrees of glucose tolerance. Subjects were randomly selected from previous population studies done in 1987-1989 at the Department of Medicine of the University of Kuopio in east Finland. Altogether, 50 subjects with normal glucose tolerance, 28 with impaired glucose tolerance, and 54 with non-insulin-dependent diabetes mellitus were studied. Correlations of insulin resistance (whole-body glucose uptake in clamp studies) with fasting or postload insulin levels were remarkably consistent, ranging from -0.58 to -0.74 (p < 0.01) in subjects with normoglycemia. In contrast, corresponding correlations were substantially weaker in subjects with impaired glucose tolerance and non-insulin-dependent diabetes. Among these subjects, only the fasting insulin level correlated significantly with insulin resistance (-0.47, p < 0.05 and -0.48, p < 0.01, respectively). The authors conclude that in population studies, only the fasting insulin level should be used as a marker of insulin resistance, particularly in subjects with abnormal glucose tolerance.     

Does the presence of diabetic nephropathy in parents influence the metabolic response in the offspring?

Non-insulin dependent (Type 2) diabetes mellitus (NIDDM) and long-term complications such as nephropathy have a strong genetic predisposition. Insulin resistance is thought to be a pathogenetic factor, predisposing genetically prone individuals to develop the microvascular complications of diabetes. To test these hypotheses, two groups of young individuals were studied: 28 offspring of parents having NIDDM and diabetic nephropathy (group 1) aged 29.5 +/- 6.1 years, BMI 25.2 +/- 4.7 kg m(-2) and 31 offspring of diabetic parents with no history of nephropathy, aged 31.6 +/- 4.1 years and BMI 26.3 +/- 4.9 kg m(-2) (group 2). All underwent a standard oral glucose tolerance test with measurement of serum insulin levels and serum lipid profile. Urine albumin:creatinine ratio (A/C ratio) and blood pressure were also recorded. Diabetes was detected in 2/28 (7.1%) and 3/31 (9.7%) and IGT was detected in 5/28 (25%) and 8/31 (25%) of groups 1 and 2, respectively. These differences were not statistically significant, but were higher than in a group of non-diabetic controls with healthy parents. Comparison of the normoglycaemic subjects (19 and 20 in group 1 and 2, respectively) showed no significant differences between blood pressure readings, fasting and 2 h plasma glucose, and lipid profiles. Plasma insulin values, fasting and 2 h, and the area under the graph were also similar in both groups, indicating an absence of higher insulin response in group 1 in comparison with group 2. These values were also not different from those in the non-diabetic controls. A delay in insulin response to glucose was noted in many of the offspring as indicated by a low deltaI/deltaG at 30'. We conclude that offspring of diabetic parents with nephropathy do not show higher risk of glucose intolerance or insulin resistance compared to those with diabetic parents without nephropathy. The relatively high plasma glucose values in the presence of normal insulin secretion in both groups of offspring of diabetic parents suggest the presence of insulin resistance.     

The additive effects of glucose and insulin on the proliferation of infragenicular vascular smooth muscle cells

PURPOSE: Peripheral vascular disease involving the infragenicular arterial tree is common in patients with diabetes mellitus (DM). Accelerated proliferation of vascular smooth muscle cells (VSMCs) plays an important role in the development of atherosclerosis. Insulin and glucose stimulate VSMC proliferation and are elevated in patients with non-insulin-dependent DM. We have previously described the mitogenic effect of insulin on VSMCs in vitro; the effects of insulin and glucose separately and in combination on the proliferation of VSMCs grown in serum-free media were studied. METHODS: Human infragenicular VSMCs isolated from diabetic patients with end-stage peripheral vascular disease undergoing below-knee amputation were used. Cells from passages 3 to 5 were grown in serum-free media with varying glucose (0.05%, 0.1%, 0.2%, 0.4%, 0.6%, and 0.8%) and insulin (no added insulin, 100 ng/mL, and 1000 ng/mL) concentrations for 6 days. RESULTS: Insulin stimulated VSMC growth at glucose concentrations more than 0.2% (0.4% glucose with no added insulin resulted in 13,073 +/- 336 cells/mL, 0.4% glucose with 100 ng/mL insulin resulted in 16,536 +/- 1175 cells/mL, 0.4% glucose with 1000 ng/mL insulin resulted in 17,500 +/- 808 cells/mL, 0.6% glucose with no added insulin resulted in 14,167 +/- 1062 cells/mL, 0.6% glucose with 100 ng/mL insulin resulted in 18,984 +/- 1265 cells/mL, 0.6% glucose with 1000 ng/mL insulin resulted in 20,450 +/- 1523 cells/mL, 0.8% glucose with no added insulin resulted in 15, 853 +/- 1650 cells/mL, 0.8% glucose with 1000 ng/mL insulin resulted in 26,302 +/- 1919 cells/mL; P <.05 compared with glucose with no added insulin). Glucose stimulated VSMC proliferation up to a concentration of 0.2% (42% and 117% higher growth at 0.1% and 0.2% glucose, respectively, compared with the baseline, P <.05), regardless of the insulin concentration in the media. The greatest growth (26,302 +/- 1919 cells/mL) occurred in the group with the highest concentration of both insulin (1000 ng/mL) and glucose (0.8% glucose; P <.05). CONCLUSION: Both insulin and glucose stimulate the growth of diabetic infragenicular VSMCs. The mitogenic effects of insulin and glucose are additive and may contribute to the development of atherosclerosis in patients with DM.     

The lung as an alternative route of delivery for insulin in controlling postprandial glucose levels in patients with diabetes

STUDY OBJECTIVES: To determine the efficacy of the lung as an alternative route of delivery for insulin in controlling glucose below diabetic levels (11.2 mmol/L) 2 h after the ingestion of a meal in patients with type 2 diabetes mellitus. DESIGN: Single-blinded, nonrandomized, placebo-controlled pilot study consisting of two visits. SETTING: A primary care facility. PATIENTS: Seven patients with type 2 diabetes mellitus. INTERVENTIONS: On the first study visit, fasting glucose levels were normalized. Then, patients inhaled 1.5 U/kg insulin by aerosol into the lungs 5 min before ingesting a test meal. On the second visit, patients inhaled placebo aerosol 5 min before ingesting the same meal. On both visits, plasma samples were collected and analyzed for glucose levels for 3 h during the postprandial state. MEASUREMENTS AND RESULTS: No one coughed after inhalation of insulin aerosol or demonstrated hypoglycemia. During the postprandial period, glucose levels were significantly lower at 20 min (5.12+/-1.08 mmol/L), 1 h (7.87+/-0.73 mmol/L), 2 h (8.05+/-1.24 mmol/L) and 3 h (7.50+/-1.43 mmol/L) following inhalation of insulin than when the placebo was used. Data for the placebo were 10.36+/-1.23 mmol/L at 20 min, 14.0+/-1.68 mmol/L at 1 h, 16.18+/-1.45 mmol/L at 2 h, and 14.37+/-2.11 mmol/L at 3h (for all comparisons, p < 0.05). On the insulin visit, glucose levels were < 11.2 mmol/L 2 h after the meal in six of seven patients. None attained this level at the placebo visit. In addition, glucose levels were within the normal postprandial range of < 7.84 mmol/L in four of seven patients 2 h after eating on the insulin visit. CONCLUSIONS: These results suggest that, once plasma glucose levels are normalized, postprandial glucose levels can be maintained below diabetic levels by delivering 1.5 U/kg insulin into the lungs 5 min before the ingestion of a meal.     

Relationship of hepatic and peripheral insulin resistance with plasminogen activator inhibitor-1 in Pima Indians

Plasminogen activator inhibitor-1 (PAI-1) is related to insulin resistance and several components of the insulin resistance syndrome, and PAI-1 levels are elevated in subjects with non-insulin-dependent diabetes mellitus. Many Pima Indians are obese, insulin-resistant, and hyperinsulinemic, and they have high rates of diabetes but a low risk of ischemic heart disease. In contrast to whites and Asians, PAI-1 activity is similar between nondiabetic and diabetic Pima Indians. We therefore examined the association of PAI-1 with hepatic and peripheral insulin action measured using the hyperinsulinemic-euglycemic clamp. To investigate if insulin per se has any effect on PAI-1 in vivo, we also assessed the effects of endogenous (during a 75-g oral glucose load) and exogenous (during hyperinsulinemic clamp) insulin on PAI-1 antigen. Twenty-one (14 men and seven women; mean age, 26.3 +/- 4.8 years) Pima Indians underwent a 75-g oral glucose tolerance test (OGTT) and a sequential hyperinsulinemic-euglycemic clamp. Peripheral insulin action was measured as absolute glucose uptake (M value) and normalized to estimated metabolic body size (EMBS). Hepatic insulin action was measured as percent suppression of basal hepatic glucose output during hyperinsulinemia. PAI-1 antigen was determined using a two-site enzyme-linked immunosorbent assay that detects only free PAI-1. PAI-1 antigen concentrations were significantly related to body mass index ([BMI] rs = .54, P = .012), waist (rs=.52, P=.016) and thigh (rs=.63, P=.002) circumference, and fasting plasma insulin concentration (rs=.59, P=.004). PAI-1 antigen concentrations were not significantly associated with peripheral glucose uptake (M value) during either low-dose (rs= -.01, P=NS) or high-dose (rs= -.11, P=NS) insulin infusion. PAI-1 antigen was negatively correlated with basal hepatic glucose output (rs= -.57, P=.013) and percent suppression of hepatic glucose output during hyperinsulinemia (rs= -.69, P=.005). However, this relationship was largely due to the confounding effects of BMI, waist and thigh girth, fasting insulin, and 2-hour postload glucose concentrations, and was not significant when controlled for these variables (partial rs= -.30, P=NS). There was no significant relationship of PAI-1 antigen concentration with glucose storage or glucose oxidation. Despite a threefold increase in plasma insulin concentrations during the OGTT, there were no significant changes in PAI-1 antigen concentrations (median, 57, 61, 55, and 44 ng/mL at 0, 60, 120, and 180 minutes, respectively; P=NS by ANOVA). During the hyperinsulinemic clamp, mean plasma insulin concentrations at the end of low-dose (240 pmol/m2/min) and high-dose (2,400 pmol/m2/min) infusions were 1,005 and 14,230 pmol/L, respectively. However, PAI-1 antigen concentrations at the end of low-dose and high-dose insulin infusions were similar to those at baseline (median, 63, 43, and 58 ng/mL, respectively; P=NS by ANOVA). PAI-1 antigen in Pima Indians is related to several components of the insulin resistance syndrome. However, direct measurement of insulin resistance indicates that hepatic but not peripheral insulin resistance is related to PAI-1 antigen. Neither endogenous nor exogenous hyperinsulinemia for short periods had any significant effect on PAI-1 antigen concentrations. Short-term hyperinsulinemia is unlikely to be an important regulator of PAI-1 in Pima Indians. The relationship of PAI-1 antigen to hepatic insulin resistance is largely dependent on the relationship of PAI-1 to indices of obesity and fasting insulin concentrations.     

Effect of cilazapril therapy on glucose and lipid metabolism in patients with hypertension

The effects of long-term monotherapy with cilazapril, an angiotensin-converting enzyme inhibitor, on blood pressure, glucose tolerance, and serum lipid profiles were prospectively investigated in 66 patients with hypertension: 23 with normal glucose tolerance and 43 with glucose intolerance (including 9 patients with non-insulin-dependent diabetes mellitus). The levels of plasma glucose, serum insulin, serum lipids, glycated hemoglobin A(lc) (Hb A(lc)), and fructosamine were determined before and during long-term (mean +/- SD, 26.2 +/- 1.2 weeks) therapy with cilazapril. A 75-g oral glucose tolerance test was performed before and during treatment. Significant reductions in both systolic and diastolic blood pressures in both patient groups were maintained during the study. Neither fasting nor post-glucose load venous plasma glucose levels were altered in either group of patients, and no patient with normal glucose tolerance developed diabetes mellitus during the study. There was no significant change in the insulinogenic index (delta serum insulin/delta venous plasma glucose at 30 minutes post-glucose load) in either group, and glucose intolerance was slightly improved with significant reductions (P < 0.01) in Hb A(lc) and fructosamine in the patient group with impaired glucose tolerance. Serum total cholesterol (TC), low-density lipoprotein cholesterol, and triglyceride levels were significantly (P < 0.01) decreased and high-density lipoprotein cholesterol levels increased in patients with hypercholesterolemia (TC levels > or = 5.69 mmol/L). These results suggest that long-term cilazapril therapy may improve glucose and lipid metabolism in hypertensive patients with impaired glucose tolerance. Cilazapril also appears to be useful as an antihypertensive agent for hypertensive patients with either impaired glucose tolerance or hypercholesterolemia.     

Troglitazone

Troglitazone decreases insulin resistance (improves insulin sensitivity), which results in reduced plasma glucose and insulin levels in patients with non-insulin-dependent diabetes mellitus (NIDDM). Risk factors for cardiovascular disease such as elevated proinsulin and triglyceride levels are also reduced by troglitazone. In clinical trials, troglitazone 200 to 800 mg daily (alone or in combination with other oral antidiabetic agents or insulin) reduced plasma or serum glucose levels and glycosylated haemoglobin compared with both baseline and placebo in patients with NIDDM refractory to other oral antidiabetic agents (usually sulphonylureas). Troglitazone was generally well tolerated in clinical trials. In patients in the US, the incidence of adverse events in troglitazone recipients was similar to that in placebo recipients.     

Calcium induces a conformational change in the ligand binding domain of the low density lipoprotein receptor

TNF-alpha may play a role in mediating insulin resistance associated with obesity. This concept is based on studies of obese rodents and humans, and cell culture models. TNF elicits cellular responses via two receptors called p55 and p75. Our purpose was to test the involvement of TNF in glucose homeostasis using mice lacking one or both TNF receptors. C57BL/6 mice lacking p55 (p55(-)/-), p75, (p75(-)/-), or both receptors (p55(-)/-p75(-)/-) were fed a high-fat diet to induce obesity. Marked fasting hyperinsulinemia was seen for p55(-)/-p75(-)/- males between 12 and 16 wk of feeding the high-fat diet. Insulin levels were four times greater than wild-type mice. In contrast, p55(-)/- and p75(-)/- mice exhibited insulin levels that were similar or reduced, respectively, as compared with wild-type mice. In addition, high-fat diet-fed p75(-)/- mice had the lowest body weights and leptin levels, and improved insulin sensitivity. Obese (db/db) mice, which are not responsive to leptin, were used to study the role of p55 in severe obesity. Male p55(-)/-db/db mice exhibited threefold higher insulin levels and twofold lower glucose levels at 20 wk of age than control db/db expressing p55. All db/db mice remained severely insulin resistant based on fasting plasma glucose and insulin levels, and glucose and insulin tolerance tests. Our data do not support the concept that TNF, acting via its receptors, is a major contributor to obesity-associated insulin resistance. In fact, data suggest that the two TNF receptors work in concert to protect against diabetes.