Endocrine Abstracts

Introduction: Women with Turner syndrome (TS) have an increased risk of diabetes mellitus (DM) the pathogenesis of which is not well understood. International guidelines for TS recommend oral glucose tolerance tests (OGTT) but the utility of this test has not been determined. We sought to establish the rate of IGT and DM and characterise the DM-phenotype in adult women with TS.

Methods: We performed OGTTs in 37 adults with TS and obtained an additional fasting sample from 18 women with established diabetes. Anthropometric data such as body fat (%) by impedance, waist circumference and BMI was calculated. HOMA-IR was calculated and subjects were tested for DM-autoantibodies; GAD, IA-2 and ZnT8. Mean age was 36 (18–68 years).

Results: OGTTs revealed 16.2% with IGT and 8.1% with the new diagnosis of DM. 28 Women with normal glucose tolerance (NGT) were compared with 27 subjects with IGT and DM. The NGT group and had a lower BMI (25.3±6.2 versus 30.6±6.2 respectively, P=≤0.001), body fat (%) (29.2±9.9 versus 35.5±9 respectively, P=0.03) and lower waist circumference (cm) (85.1±13.1 versus 97.8±12.4 respectively, P≤0.001) compared to women with abnormal glucose tolerance. However no significant difference was found in HOMA-IR between NGT and IGT/DM subjects (1.6±1.6 versus 2.3±1.6 respectively, P=0.23). Positive DM- related antibodies in NGT were; GAD=1/28 (3.6%), IA-2=1/28 (3.6%) and ZnT8=2/28 (7.1%) compared to those with IGT/DM GAD=4/24 (14.8%), IA-2=1/24 (3.7%) ZnT8=1/24 (3.7%) (P=.24; P=.91; P=.46 respectively). Of the 18 DM subjects, 4 used insulin, 13 used oral anti-diabetic drugs and 1 was diet controlled. GAD positive autoantibodies were found in 3/4 insulin dependent DM subjects compared to 1/14 non- insulin dependent subjects (P=.03).

Conclusions: We highlight the importance of OGTT as part of management although the rate of progression to DM in TS is unknown. The rate of DM was higher than previously reported. TS-DM was characterised by a increased waist circumference and BMI and percent body fat which is consistent with T2DM. Insulin requiring DM was associated with positive GAD autoantibodies. Screening for diabetes with secondary autoantibody testing may be indicated for optimal health surveillance for women with TS.