Relation between the serum level of C-peptide and risk factors for coronary heart disease and diabetic microangiopathy in patients with type-2 diabetes mellitus

Syndrome X is used to describe a constellation of factors that lead to coro nary heart disease (CHD): hypertension, hyperinsulinemia, impaired glucose tolerance, and an abnormality in lipid metabolism. We investigated the rela tionship between serum levels of C-peptide immunoreactivity (CPR) and diabe tic complications in 256 patients with type-2 diabetes mellitus. The serum level of CPR was measured by radioimmunoassay (RIA). Diabetic patients were divided into 3 groups according to the serum level of CPR as follows: low CPR (n = 19. <0.7 ng/ml). normal CPR (n = 174, 0.7 to 2.2 ng/ml) and high C PR (n = 63, >2.2 ng/ml). The body mass index (BMI) and the serum level of t riglycerides were significantly higher in the high CPR group (P < 0.05, res pectively) compared with normal CPR group. The prevalence of hypertension w as significantly higher in the high CPR group than in the other 2 groups (l ow CPR: 16%, normal CPR: 28%, high CPR: 38%). The frequency of the number o f patients receiving insulin therapy was greater in the low CPR group than in the other 2 groups, (low CPR: 58%, normal CPR: 15%, high CPR: 11%). The serum CPR level was significantly lower in patients with than without proli ferative retinopathy or macroalbuminuria. Our conclusion is that the presen t data suggest that an increased serum level of CPR is associated with obes ity, elevated serum triglycerides, and hypertension in patients with type-2 diabetes mellitus. A low CPR level leading to hyperglycemia is associated with the: progression of diabetic microangiopathies such as retinopathy and nephropathy.