Abstract

Objective: We have previously shown that hypogonadotrophic hypogonadism is common in middle-aged patients with type 2 diabetes (T2D) but not with type 1 diabetes (T1D). We have now investigated the total testosterone (TT) and free testosterone (FT) concentrations in young (age 18-35 years) T1D and T2D patients.

Research Design and Methods: In this study carried out in a tertiary referral center, serum concentrations of TT and FT were measured in 38 T1D (mean age:26.45 ± 0.89years) and 24 T2D (mean age: 27.87±0.97years). The mean BMI of T1D and T2D patients was 27.41±1.18 and 38.55±2.04kg/m² respectively (p<0.001).

Results: The mean TT concentration of T1D and T2D patients was 22.89±1.23 and 11.14±0.99nmol/l respectively (p<0.001). The mean FT concentration of T1D and T2D patients was 0.489±0.030 and 0.296±0.022nmol/l respectively (p<0.001). 8 out 24(33%) of T2D patients had subnormal FT concentrations (<0.225nmol/l). Using an age-based reference range, 14 out of 24(58%) of T2D patients had low FT concentrations (<0.278 nmol/l). 3 out of 38(8%) of T1D patients had FT concentrations below the lower limit of normal (p=0.02 when compared to T2D). LH and FSH concentrations in T2D patients with low FT concentrations were in the normal range and were similar to those in T1D patients.

Conclusions: Young T2D patients have significantly lower plasma concentrations of TT and FT, and inappropriately low LH and FSH concentrations with a very high prevalence of hypogonadotrophic hypogonadism, when compared to T1D patients of a comparable age. The potential implications for their sexual and reproductive function in the prime reproductive years are profound.