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 microalbuminuria. 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 HbA1c had a significant and independent inverse influence on SHBG (r2 = 0.77, p < 0.001). With log AER as the dependent variable, low SHBG, low IGF-1, HbA1c, and age added to the regression (r2 = 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 HbA1c. In turn, low SHBG seems to be independently associated to elevated AER in these patients.(ABSTRACT TRUNCATED AT 250 WORDS)