Plasma adiponectin concentration and tumor necrosis factor-alpha system activity in lean non-diabetic offspring of type 2 diabetic subjects.

OBJECTIVE: There is growing evidence that adiponectin function is related to the pathogenesis of insulin resistance. Insulin resistance might be present even in lean subjects with a strong family history of type 2 diabetes. The aim of the study was to look for adiponectin's role in the pathogenesis of insulin resistance in offspring of type 2 diabetic patients, and its relation to the activity of the tumor necrosis factor (TNF)-alpha system. RESEARCH DESIGN AND METHODS: The study was carried out in 23 lean offspring of type 2 diabetic subjects and in 23 controls matched for age, sex and body mass index. The oral glucose tolerance test for glucose and insulin estimations and hyperinsulinemic, euglycemic clamp studies were performed in all patients. The plasma concentration of adiponectin, TNF-alpha, soluble TNF receptors 1 and 2 (sTNFR1, sTNFR2), HbA1c, total cholesterol, high-density lipoprotein (HDL)-cholesterol, low-density lipoprotein-cholesterol and triglycerides were estimated. RESULTS: The insulin sensitivity index, normalized for fat-free mass (M(ffm)) and adiponectin concentrations were markedly decreased in offspring of type 2 diabetic subjects compared with the control group (P = 0.0046 and P = 0.00058 respectively). TNF-alpha and sTNFR1 concentrations did not differ between the studied groups; however the concentration of sTNFR2 was markedly increased in the offspring of type 2 diabetic patients (P = 0.0002). Adiponectin concentration was positively correlated to the insulin sensitivity index (r = 0.34; P = 0.020) and to HDL-cholesterol (r = 0.29, P = 0.047) and was inversely related to sTNFR2 (r = -0.33, P = 0.027). CONCLUSIONS: The obtained results suggest that adiponectin could play a role in the pathogenesis of insulin resistance in lean offspring of type 2 diabetic subjects.

Insulin resistance in the first-degree relatives of persons with type 2 diabetes.

BACKGROUND: Type 2 diabetes is characterized by impaired insulin secretion and insulin resistance. Both genetic and environmental factors are thought to play a role in the pathogenesis of this disease. Obesity is associated with increased risk of type 2 diabetes, but some metabolic abnormalities may also be present in lean, predisposed subjects. The aim of the present study was to assess insulin sensitivity in lean normoglycemic offspring of parents with type 2 diabetes. MATERIAL/METHODS: We examined 17 lean offspring (BMI<25 kg x m-2) whose parents had type 2 diabetes, and 17 age, sex and BMI-matched subjects without family history of diabetes as controls. Anthropometric and biochemical measurements, oral glucose tolerance test (OGTT), and euglycemic hyperinsulinemic clamp were performed. RESULTS: The subjects did not differ in anthropometric measurements, and all had normal glucose tolerance according to WHO criteria. Offspring of type 2 diabetic parents were markedly more hyperinsulinemic (p<0.05) and insulin resistant (p<0.005). The ratio of the increase in insulin to the increase in glucose during the first 30 minutes of the OGTT, a crude index of first-phase insulin secretion, did not differ between groups. Insulin sensitivity was negatively related to fasting plasma insulin (r=-0.67, p<0.001) and non-esterified fatty acids (r=-0.43, p<0.02). CONCLUSIONS: Insulin resistance is present even in young lean subjects at high risk to develop type 2 diabetes. Our data suggest that insulin resistance may be a primary abnormality in the pathogenesis of this disease.