Performance characteristics of postpartum screening tests for type 2 diabetes mellitus in women with a history of gestational diabetes mellitus: a systematic review.

BACKGROUND: Women with a history of gestational diabetes mellitus are at high risk for type 2 diabetes mellitus. We systematically reviewed and synthesized the literature on the sensitivity, specificity, and reproducibility of postpartum screening tests for type 2 diabetes in women with prior gestational diabetes to inform screening guidelines.
METHODS: We searched electronic databases through October 1, 2008. Two investigators independently reviewed titles, abstracts, and articles, performed serial data abstraction, and independently assessed quality. We calculated standard errors and confidence intervals for sensitivity and specificity using the exact binomial formula.
RESULTS: Eleven studies contained 13 evaluations of a comparison screening test with the 2-h 75-g oral glucose tolerance test (OGTT) reference. All studies used a cross-sectional study design. There were ten comparisons of a single fasting blood glucose (FBG) >=7.0 mmol/L (>=126 mg/dL) with the OGTT. The sensitivity ranged from 14%-100% in five studies using the 1985 World Health Organization's (WHO) criteria as the reference and from 16%-89% in five studies using the 1999 WHO criteria as the reference. Variation in the sensitivities may be due to the limited number of comparisons, differences in populations, and timing of screening. There were high losses to follow-up, limiting generalizability.
CONCLUSIONS: When compared with the OGTT, the single FBG alone was not consistently reported to be a sensitive screening test for type 2 diabetes in women with a history of gestational diabetes. Longitudinal studies are needed to address the natural history of glucose metabolism in women with a history of gestational diabetes, the optimal approach to diagnostic testing for type 2 diabetes in this population, and the short-term and long-term outcomes of testing.