A 10-year retrospective analysis of pregnancy outcome in pregestational Type 2 diabetes: comparison of insulin and oral glucose-lowering agents

Aims To review the use of oral glucose-lowering agents (OGLA) in pregnant women with Type 2 diabetes mellitus. Methods Retrospective analysis of outcomes and their predictors in singleton pregnancies >= 24 weeks managed at Groote Schuur hospital, Cape Town, South Africa from 1991 to 2000. There were 379 pregnancies, subdivided into three groups according to therapy: OGLA alone, converted from OGLA to insulin, insulin alone or converted from diet alone to insulin. The OGLA used were metformin and glibenclamide. Results Mean glycated haemoglobin (HbA(1c)) was similar at booking and throughout pregnancy in all groups. In the OGLA alone, converted from OGLA to insulin and insulin alone/converted from diet alone to insulin groups, fetal anomaly rates were comparable: 5.7%, 2.0% and 0.0%, P = 0.2, respectively; whereas perinatal mortality rates (per 1000 births) were: 125, 28, 33, P = 0.003, respectively. Booking HbA(1c) was independently associated with fetal anomaly [odds ratio (OR) 1.48; 95% confidence interval (CI) 1.11, 1.97; P = 0.006]. The specific OGLA used in the first trimester was not associated with the occurrence of fetal anomaly. Last HbA(1c) (OR 1.65; 95% CI 1.16, 2.42; P = 0.005) and fetal anomaly (OR 15.18; 95% CI 2.43, 93.37; P = 0.005) were independently associated with perinatal mortality. Conversion from OGLA to insulin was protective for perinatal mortality compared with OGLA alone treatment (OR 0.220; 95% CI 0.061, 0.756; P = 0.024). No perinatal mortality was observed in women on metformin alone. Conclusions These data suggest that metformin and glibenclamide are not teratogenic but that it is advisable to replace OGLA, in particular glibenclamide, with insulin when women book for pregnancy care to reduce perinatal mortality rates.