New classification and diagnostic criteria for diabetes mellitus

The new Classification and Diagnostic Criteria for Diabetes Mellitus (DM), prepared by a group of experts from the American Diabetes Association is presented and analyzed. On an etiopathogenic basis, it designates Insulin Dependent and Non Insulin Dependent as Type 1 and Type 2 respectively. It specifies DM having specific known causes. It maintains Gestational Diabetes and Glucose Intolerance and adds the Impaired Fasting Glucose Condition. It recommends fasting plasma glucose for search and diagnosis, and lowers the level to > or = 126 mg/dl instead of > or = 140 mg/dl, due to its association with chronical complications of DM. It maintains the diagnostic criteria of random and post charge glycemia > or 200 mg/dl. It does not alter the glucose intolerance figure (140-200 mg/dl in OGTT) and introduces fasting abnormality > or = 110 and < 126 mg/dl. It encourages the search with fasting glucose every 3 years in individuals aged over 45, and at more frequent intervals in younger individuals with high risk factors. Analysis of the report allows to conclude that, although the classification does not introduce any significant change in daily clinical use, its pathogenic orientation makes future innovations possible. The preferential use of fasting glucose > or = 126 mg/dl for diagnosis of DM has theoretical basis and practical advantages. Identification of individuals with impaired fasting glucose allows to detect, in a simple manner, a high risk group in which to start preventive measures. However, there is a percentage of cases which are not diagnosed by fasting glycemia, but are diagnosed by OGTT, therefore the latter should not be discarded.     

The new diagnosis and classification of diabetes mellitus

We are in the midst of an epidemic of diabetes, and the prevalence appears to be especially marked within Delaware. To prevent tragic long-term complications of diabetes, and to minimize the enormous costs associated with treating them, an emphasis must be placed on the early diagnosis and aggressive management of diabetes. The changes in the classification, diagnosis and screening for diabetes should help to redirect the focus to one of preventive care.     

Modern diagnosis and classification of diabetes mellitus

In July 1997, the American Diabetes Association (ADA) has published new recommendations for the diagnosis and classification of diabetes mellitus. Except for gestational diabetes they should be identical to the new WHO recommendations (not yet published). From now on, only the fasting glucose should be used for clinical routine. The oral glucose tolerance test is no longer recommended for this purpose. The diagnostic cut-off level for fasting glucose was decreased from 140 mg/100 ml (venous plasma) to 126 mg/dl, and the range between 110 and 125 mg/100 ml was defined as impaired fasting glucose (IFG), a new diagnostic category introduced in analogy to impaired glucose tolerance (IGT). The lower diagnostic cut-off level for fasting glucose has been proposed because the risk of developing diabetic late complications (predominantly at the vascular system) is already increased in blood glucose ranges thought to be normal. The diagnostic criteria for gestational diabetes are unchanged and still discrepant between ADA and WHO. The two major forms of diabetes should be designated only as type 1- and type 2-diabetes with respect to etiology and pathogenesis. Type 1-diabetes was subdivided into an immune-mediated and into an idiopathic form. MODY (maturity-onset type diabetes in young people) was listed separately from type 2-diabetes under the category of genetic defects of beta-cell function, also mitochondrial diabetes (maternally inherited diabetes and deafness). Malnutrition-related diabetes has been omitted as a major form of diabetes.     

A new subtype of diabetes mellitus: maternally inherited diabetes and deafness (MIDD)

Diabetes mellitus comprises many subtypes, the pathogenesis of each of which involves a combination of inherited and environmental factors. Recently a new subtype of diabetes mellitus was recognized in a Dutch pedigree, designated as 'maternally inherited diabetes and deafness' (MIDD). Impaired hearing is an associated phenomenon of the disease. Approximately 1.3% of all diabetic cases in the Netherlands exhibit the MIDD subtype. MIDD shows a strictly maternal heredity. In MIDD there is a guanine-for-adenine substitution at position 3243 in mitochondrial DNA. Mitochondria carrying this mutation exhibit a decreased functionality. In carriers of the MIDD mutation the insulin secretion by the pancreas in response to stimulation by glucose is impaired.     

Diabetes in older adults: comparison of 1997 American Diabetes Association classification of diabetes mellitus with 1985 WHO classification

BACKGROUND: We aimed to compare the prevalence of abnormal glucose tolerance identified by the 1985 WHO and the 1997 American Diabetes Association (ADA) diagnostic categories based on information collected in the Cardiovascular Health Study, an epidemiological study of elderly people. METHODS: We measured glucose concentrations during fasting and 2 h after a 75 g oral glucose-tolerance test in participants aged 65-100 years in the Cardiovascular Health Study. From a 1989 cohort, we analysed the glucose measurements of 4515 individuals without a previous diagnosis of diabetes and of 262 additional measurements from an African-American cohort recruited in 1992-93. FINDINGS: In the 1989 cohort, the prevalence of untreated diabetes with ADA diagnostic fasting criteria was 7.7% versus a prevalence of 14.8% by the WHO criteria. In the African-American cohort, the prevalence of untreated diabetes was 2.7% with ADA criteria and 11.8% with WHO criteria. 3509 (77.7%) of the 4515 participants in the 1989 cohort had normal glucose concentrations according to ADA fasting criteria, compared with 2401 (53.2%) according to WHO criteria. In the African-American cohort, the corresponding numbers were 239 (91.2%) versus 153 (58.4%). All differences in prevalence of abnormal glucose tolerance between ADA and WHO classifications were significant (p<0.0001). INTERPRETATION: Among elderly individuals, there was a significant difference in the prevalence of diabetes identified by the WHO diagnostic criteria based on oral glucose-tolerance test and the ADA fasting criteria. Consequently, many individuals currently classified as non-diabetic according to ADA criteria would previously have had a diagnosis of diabetes according to WHO criteria. Longitudinal studies are needed to assess the value of the criteria in the identification of individuals at increased risk of diabetes-associated chronic complications.     

Gestational diabetes mellitus and subsequent development of overt diabetes mellitus

GDM develops in 1-3% of all pregnancies. Women with GDM are characterized by a relatively diminished insulin secretion coupled with a pregnancy-induced insulin resistance primary located in skeletal muscle tissue. The cellular background for this insulin resistance is not known. The binding of insulin to its receptor and the subsequent activation of the insulin receptor tyrosine kinase have significant importance for the cellular effect of insulin. Thus, the pathogenesis to the insulin resistance was studied by investigating insulin receptor binding and tyrosine kinase activity in skeletal muscle biopsies from women with GDM and pregnant controls. No major abnormalities were found in GDM wherefore it is likely that the insulin resistance is caused by intracellular defects distal to the activation of the tyrosine kinase. Glucose tolerance returns to normal postpartum in the majority of women with GDM. However, previous studies, in populations quite different from a Danish population, have shown that women with previous GDM have a high risk of developing overt diabetes mellitus later in life. Hence, we aimed to investigate the prognosis of women with previous GDM with respect to subsequent development of diabetes and also to identify predictive factors for the development of overt diabets in these women. A follow-up study of diet treated GDM women diagnosed during 1978 to 1985 at the Rigshospital, Copenhagen was performed. Glucose tolerance was evaluated in 241 women (81% of the GDM population) 2-11 years after pregnancy. Abnormal glucose tolerance was found in 34.4% of the women (3.7% IDDM, 13.7% NIDDM, 17% IGT) in contrast to a control group where none had diabetes and 5.3% had IGT. Logistic regression analysis identified the following independent risk factors for later development of diabetes: a high fasting glucose level at diagnosis of GDM, a delivery more than 3 weeks before term, and an abnormal OGTT 2 months postpartum. Low insulin secretion at diagnosis of GDM was also an independent risk factor. The presence of ICA and GAD-autoantibodies in pregnancy was associated with later development of IDDM. In another study the following techniques: hyperinsulinaemic euglycaemic clamp, indirect calorimetry and tritiated glucose infusion were used to evaluate insulin sensitivity in glucose tolerant nonobese women with previous GDM and controls. A decreased insulin sensitivity due to a decreased non-oxidative glucose metabolism in skeletal muscle was found in women with previous GDM. Hence, the activity of three key enzymes in intracellular glucose metabolism (GS, HK and PFK) was studied in skeletal muscle biopsies obtained in the basal state and after 3 h hyperinsulinaemia, with the aim to identify the cellular defects causing the decreased insulin sensitivity. However, no abnormalities in enzyme activity was found. The same group of previous GDM women had a relatively reduced insulin secretion evaluated by the IVGTT. A longitudinal study of 91 GDM women showed a relatively reduced insulin secretion to oral glucose in pregnancy, postpartum as well as 5-11 years later. Thus the present review has shown that even nonobese glucose tolerant women with previous GDM are characterized by the metabolic profile of NIDDM i.e. insulin resistance and impaired insulin secretion. Hence, the combination of this finding together with the significantly increased risk for development of diabetes indicates that all women with previous GDM should have a regular assessment of their glucose tolerance in the years after pregnancy. The first OGTT should be performed around 2 months postpartum in order to diagnose women already diabetic and to identify women with the highest risk for later development of overt diabetes. Women with previous GDM comprise a target group for future intervention trials with the aim to prevent or delay development of NIDDM and IDDM.     

Clinical criteria for the use of a decision-making framework for the medically compromised patient: hypertension and diabetes mellitus

In this article, clinical criteria for the staging of disease severity in patients with hypertension and diabetes mellitus are presented. This paper is intended to supplement a previous article by the authors on the use of clinical criteria for the classification of patients with ischemic heart disease and chronic obstructive pulmonary disease and the use of a decision-making framework for the medically compromised patient. Hypertension and diabetes mellitus are discussed in terms of pathophysiology, risk factors, clinical manifestations of disease and disease progression. The article will allow practitioners to stage patients with hypertension and diabetes mellitus and to apply this staging to the previously established clinical decision-making framework for medically compromised patients.     

Zinc and diabetes mellitus

In patients with type 1 and 2 diabetes was frequently found: low blood zinc levels, high zincuria, severe and ubiquitous cellular depletion of zinc, increased basal and after loading blood mineral clearance, and hyperglycaemia due to the reduction of pancreatic insulin secretion and to the reduced biological action of the hormone on liver, as a consequence of chronic zinc deficit. Strong endocellular zinc depletion in diabetics; low insulin secretion; insulin biological action decrease for zinc deficit; IG-I concentration decrease, that happens in this condition; insulin and IGF-I resistance; insulin and IGF-I receptors depletion in diabetics: are strong arguments for zinc pharmacological supplementation, in gastric protective formulation, to avoid gastroenteric problems.     

Diuretics and diabetes mellitus

The term "diuretics" describes a concerning pharmacological action and side effects heterogeneous class of drugs. The special advantage of using diuretics includes reducing edema and expanded plasma volume often associated with hypertension and cardiovascular disease. Diuretics are one of the 5 major classes of antihypertensive agents recommended for the initial drug therapy of hypertension. However, currently treatment of hypertension with diuretics is controversial, because of potentially adverse effects on the cardiovascular risk profile, including deterioration in glucose control especially in patients with impaired glucose tolerance. Additionally there is concern about excess mortality associated with diuretic therapy and diabetes mellitus. The metabolic side effects on glucose metabolism and lipid profile are related to the type of diuretic and its dosage. The adverse effects of thiazides on insulin action, glycemia and lipid profile are dose dependent and can be minimized by using low doses. In contrast, indapamide seems not to alter glucose metabolism and lipid profile. The choice of diuretic depends on concomitant disease. In patients with nephropathy potassium sparing agents should not be used, however furosemid can be used even in high doses. Beside focus on indication of diuretics in patients with diabetes and their metabolic side effects treatment of therapy resistant hypertension in these patients are discussed in this review.     

Smoking and diabetes mellitus

Diabetic patients die mostly from chronic vascular complications, in particular ischaemic heart disease (specially type II diabetics) and renal failure associated with diabetic nephropathy (in particular type I diabetics). Smoking--one of the basic risk factors of atherosclerosis and its complications--accelerates in diabetics the atherosclerotic process and enhances the risk of cardiovascular complications. Smoking causes endothelial dysfunction, as well as deterioration of diabetic nephropathy and retinopathy. Smoking accelerates by various mechanisms the coagulation process and causes thus deterioration of the hypercoagulation state in diabetics. Anti-smoking intervention should be along with a diabetic diet the basic step in non-pharmacological treatment of diabetics.