INDICATIONS OF LOW SEX-HORMONE BINDING GLOBULIN (SHBG) IN YOUNG FEMALES WITH TYPE-1 DIABETES, AND AN INDEPENDENT ASSOCIATION TO MICROALBUMINURIA

Sex hormone binding globulin (SHBG) is normally decreased during puberty and inversely related to insulin resistance. Microalbuminuria is rare before puberty in Type 1 diabetes implicating that sex hormones may contribute to its development. We investigated SHBG levels in young females with >5 years of Type 1 diabetes, and the association to microalbuminuria. Ten diabetic females with, and 15 without microalbuminuria, and 17 healthy controls in pubertal stage 4-5 were compared regarding anthropometric data, fasting serum levels of SHBG, testosterone, insulin, insulin-like growth factor-1 (IGF-1), lipids and lipoproteins. Multiple regression analyses were performed to study variables with independent influences on SHBG and albumin excretion rate (AER), respectively, in Type 1 diabetes. SHBG was lower and testosterone/SHBG ratio higher in normoalbuminuric females with diabetes than in controls. This was further emphasized in diabetic patients with microaibuminuria. IGF-1 was lower in Type 1 diabetes than in controls, and significantly decreased in microalbuminuric as compared to normoalbuminuric diabetic patients. IGF-1 was only correlated to SHBG in healthy controls. In Type 1 diabetes, applying stepwise multiple regression analysis, insulin dose, BMI, and HbA(1C) had a significant and independent inverse influence on SHBG (r(2) = 0.77, p < 0.001). With log AER as the dependent variable, low SHBG, low IGF-1, HbA(1C), and age added to the regression (r(2) = 0.65, p=0.004), whereas BMI, insulin dose and blood pressure did not. In conclusion, SHBG is decreased in young females with Type 1 diabetes, influenced by increased insulin requirements, BMI and HbA(1C). In turn, low SHBG seems to be independently associated to elevated AER in these patients. Prospective studies are necessary to confirm our results.