Insulin sensitivity was assessed using the euglycaemic clamp technique in eight type I diabetic patients (after overnight blood glucose normalization with an artificial pancreas) and in six healthy subjects. Basal insulin concentrations were higher in diabetic patients (25±4 µU/ml) than in control subjects (17±1 µU/ml;
P<0.05). insulin="" infusion="" of="" 0.5,="" 1.0,="" 2.0="" and="" 5.0="" mu/kg="" per="" min="" during="" subsequent="" 2-h="" periods="" resulted="" in="" similar="" mean="" steady-state="" insulin="" concentrations="" in="" both="" groups.="" the="" mean="" dextrose="" requirements="" during="" the="" last="" 40="" min="" of="" each="" period="" were="" nevertheless="" decreased="" in="" diabetic="" patients="" (1.6±0.5,="" 3.5±0.8,="" 6.5±0.7,="" 10.2±0.7="" mg/kg="" per="" min)="" as="" compared="" with="" control="" subjects="" (4.7±0.3,="" 8.2±0.9,="" 10.2±0.9,="" 12.4±0.9="" mg/kg="" per="" min).="" at="" low="" insulin="" concentrations="" dextrose="" requirements="" were="" diminished="" in="" all="" diabetic="" subjects.="" at="" the="" highest="" insulin="" levels,="" individual="" dose-response="" curves="" from="" only="" four="" patients="" were="" within="" the="" normal="" range.="" under="" basal="" conditions,="" the="" monocyte="" receptor="" number="" was="" significantly="" reduced="" in="" diabetic="" patients="" (17,500±2,800="" sites/cell)="" as="" compared="" with="" control="" subjects="" (26,700±2,500="">
P<0.05), whereas="" there="" were="" no="" differences="" regarding="" empty="" site="" affinities.="" receptor="" data="" did="" not="" differ="" in="" patients="" with="" normal="" and="" decreased="" maximal="" dextrose="">
Insulin resistance is apparently a common feature of type I diabetes at serum insulin concentrations of approximately 100 µU/ml. Normalization of the insulin effect by higher insulin concentrations is not possible in all patients. Insulin antibodies at concentrations observed in this study (<0.16 mu/ml)="" do="" not="" contribute="" significantly="" to="" insulin="" resistance;="" receptor="" and="" postreceptor="" defects="" are="" possibly="" more="">
Key words Type I diabetes - Insulin resistance - Euglycaemic clamp - Insulin receptor binding - Insulin antibodies
I.N. and P.A. were fellows of the Deutscher Akademischer Austauschdienst 1981/82 and 1983/84