Endocrine Abstracts

The current NICE guidelines outline testing for Gestational Diabetes Mellitus (GDM) via two different pathways: self monitoring glucose and two 75g 2-h OGTTs in women identified as high risk for GDM. The first of these takes place immediately after their first booking and the second between 24 - 28 weeks. Pregnant women who have undergone bariatric surgery often have delayed gastric emptying and absorption which will interfere with the traditional OGTT and the testing values of glucose. We present a case of a late diagnosis of GDM in a 33 year old Caucasian female who underwent sleeve gastrectomy a decade ago. Her booking BMI was 39 kg/m2. Based on this BMI she would be a GDM risk. The booking HbA1c was 32 mmol/mol. She successfully passed the recommended OGTT at 24-28 weeks. However, on further investigation via blood glucose monitoring at home, she was found to have unusually high fasted glucose >9 mmol/l and 1 h post-prandial blood glucose levels >8 mmol/l, indicating GDM. Her fetal scans did not indicate any evidence of macrosomia or placental insufficiency. She was started on metformin 500mg BD and glucose monitoring at home became within pregnancy target range. This case highlights the lack of sensitivity of OGTT in post bariatric surgery pregnancies and therefore increases risks associated with untreated GDM on maternal/fetal health and pregnancy outcomes. The NICE recommended OGTT had not been successful in identifying this patient’s gestational diabetes mellitus. The implications of this late diagnosis suggest that current guidelines are not adequate at diagnosing GDM in post-bariatric surgical patients. This results in under diagnosis and subsequent lack of treatment, which may ultimately result in poorer patient health outcomes. We propose post bariatric surgery pregnancies to be tested with regular glucose monitoring and to base treatment on home monitoring results.