The relationship between the IGF-I system and its binding proteins and microvascular reactivity in type 1 diabetes mellitus
Abstract
The system of IGF-I and its binding proteins may be involved in the pathogenesis of vascular damage in Type I diabetes. The aim of this study was to analyze the relationship between this system and the microvascular reactivity in Type I diabetes as measured by laser-Doppler flowmetry.
Twenty-two Type I diabetic patients (13 women and 9 men) with microangiopathy and fifteen healthy subjects (8 women and 7 men) were examined clinically, underwent laser-Doppler flowmetry and intima-media thickness measurements. Fasting serum levels of IGF-I, free IGF-I, IGFBPs and lipids were examined.
The microvascular reactivity was impaired in Type 1 diabetic patients. Maximal perfusion during post-occlusive reactive hyperemia (PORHmax) and during thermal hyperemia (THmax) was significantly decreased in Type I diabetes (p<0.01).
Percentage perfusion increase in both tests (PORH and TH) was lower in Type 1 diabetes mellitus (p<0.01) and the reaction after heating was slower in diabetic patients (THmax/t) (p<0.01). We did not find any significant dependence of microvascular reactivity on the parameters of IGF-I or its binding proteins.
We conclude that the microvascular reactivity is impaired in Type I diabetes mellitus, but this impairment is not clearly dependent on the activity of the IGF-I system. It is probably only a complementary pathogenic factor.