Insulin resistance is found patients with diabetes mellitus type 2 as well as in obese subject without diabetes. The objective of our investigation was to compare the action of insulin in morbidly obese subject with and without diabetes and in diabetic subject with different degrees of obesity. A total of 36 diabetic were examined, divided according to the BMI into morbidly obese (DMTO: BMI > 40 kg/m-2.n = 6) those with medium severe obesity (DMSO: BMI 31-40 kg.m-2.n = 16), with slight overweight DMLO. BMI 26-91 kg.m-2.n = 9) and non-obese diabetics (DMBO). BMI 21-26 kg.m-2.n = 5). The group of morbidly obese non-diabetic subject (NDTO, BMI > 40 kg.m-2.n = 5) and non-obese healthy subject (C, BMI < 26 kg.m-2, n = 12) served as control. All examined subject were of similar age the diabetic subject had similar values of indicator of diabetic control (HbA1c was 7.1 +/- 0.5%). The examination was made using the method of an isoglycaemic hyperinsulinaemic clamp on a Biostator at an insulin infusion rate of 1mU.kg-1.min-1 for a period of 20 minutes. The results of the index of tissue sensitivity to insulin revealed a markedly deteriorated action of insulin in morbidly obese diabetes and non-diabetics in relation to control group of healthy slim controls (M/I, DMTO: 12.4 +/- 7.3 and NDTO: 9.2 +/- 4.1, p < 0.001, mumol.kg-1.min-1 na mU.l-1 x 100), in midly and medium obese diabetics the insulin resistance was of difference grades (M/I, DMLO: 34.2 +/- 9.3, p < 0.05, and DMSO: 25.9 +/- 18.5 p < 0.001 mumol.kg-1.min-1 na mU.l-1 x 100. Non-obese diabetic and non-diabetic subject had a normal insulin action (M/I, DMBO: 58.3 +/- 29.4 and C: 48.9 +/- 5.0 mumol.kg-1.min-1 per mU.l-1 x 100. The metabolic glucose clearance differed however between diabetic and non-diabetic subject (MCRG, DMTO: 2.0 +/- 0.4, p < 0.001, DMSO: 3.8 +/- 2.4, p < 0.001, DMSO: 5.4 +/- 1.7, p < 0.05 v.s. C: 8.6 +/- 1.1 and NDTO: 3.8 +/- 1.5, p < 0.001 ml.kg-1.min-1). The statistical significance is related to the control group of slim healthy subject. From this ensues that no significant difference was found between slim diabetic and non-diabetic subjects in the majority of parameters expressing the action of insulin with the exception of the metabolic glucose clearance. At the same time the authors found in the whole group of 53 examined subject a statistically significant correlation between the BMI and the index of tissue sensitivity for insulin (M/I) (r = -0.55, p < 0.001). On examination of characteristics of insulin receptors on erythrocytes the authors found a reduced number in diabetic subject as compared with the two control groups (p < 0.05). It may thus be concluded from this investigation that the BMI has a decisive role in the action insulin.

Keywords: Body Mass Index; Body Weight; Diabetes Mellitus /metabolism/; Diabetes Mellitus, Type 2 /metabolism/; Female; Humans; Insulin /metabolism/; Insulin Resistance; Male; Middle Aged; Obesity; Obesity, Morbid /metabolism/