“Gestational diabetes (GDM) strongly predicts future development of Type 2 diabetes and abnormal glucose tolerance can persist postpartum leading to impaired fasting glucose (IFG), impaired glucose tolerance (IGT) and Type 2 diabetes,” write Sarah Kwong, MD, from the University of Alberta in Edmonton, Canada, and colleagues.
“Compared with an oral glucose tolerance test (OGTT), fasting plasma glucose (FPG) has greater reproducibility but may lack sensitivity to identify women with IGT or Type 2 diabetes. The main study objectives were to assess adherence with postpartum testing, to identify factors associated with non-adherence, and to compare the sensitivity of FPG versus a 75g OGTT in detecting postpartum glucose intolerance.”
The study cohort consisted of 1,006 women with gestational diabetes who were attending a pregnancy diabetes clinic, of whom 97 were excluded. Only 438 women (48%) underwent postpartum screening. Compared with women who were screened, women who did not undergo screening were more likely to have higher parity (1.10 vs 0.87) and were less likely to need insulin for management of their gestational diabetes.
Among women who were tested postpartum, 89 (21%) had an abnormal result, only 25 (28%) of whom had an abnormal fasting plasma glucose result. Women who were non-Caucasian or who had previous gestational diabetes, higher hemoglobin A1c or oral glucose tolerance test values during pregnancy, or treatment with insulin were most likely to have abnormal postpartum diabetes screening results.
“The rate of postpartum diabetes screening is low and FPG lacks sensitivity as a screening test in comparison with OGTT,” the study authors write. “Despite attempts to improve adherence, less than 50% of our cohort underwent postpartum testing for glucose intolerance, and only higher parity and lack of insulin use were significantly associated with non-adherence to testing…. Given the rising incidence of post-gestational hyperglycemia and a lack of reliable predictors to identify non-adherence to post partum testing, universal screening with an OGTT should be applied to this high risk population.”
Diabetes Care. Published online September 9, 2009. Abstract