Glucose targets in pregnant women with diabetes: a systematic review and meta-analysis

Glucose-lowering treatments are used during pregnancy to reduce the risk for complications in the mother and offspring, yet treatment targets have not been established.

Our objective was to appraise and summarize the available evidence regarding the association between different blood glucose targets during pregnancy and fetal and maternal outcomes.

We searched Medline, EMBASE, Cochrane Library, Web of Science, Scopus, PsycInfo, and CINAHL through May 2011 for randomized trials and observational studies that enrolled women with diabetes during pregnancy and reported planned or achieved glucose targets. We used random-effects meta-regression models to estimate the odds ratio for the association of outcomes of interest and glucose targets. When possible, we adjusted for diabetes type, trimester, and diabetes treatment.

We included 34 studies enrolling 9433 women. The studies had moderate to high risk of bias due to evidence of reporting bias and insufficient adjustment for important covariates, particularly maternal body mass index. A fasting glucose target of <90 mg/dL was the most commonly reported and the one most strongly associated with reduced risk of macrosomia (odds ratio = 0.53, 95% confidence interval = 0.31-0.90, P = .02) for women with gestational diabetes during the third trimester. For type 1 and type 2 diabetes, and for pre- and postprandial targets, data were sparse and inconclusive.

Evidence warranting very low confidence in the estimates suggests that a fasting glucose target of <90 mg/dL is associated with a lower risk of macrosomia and other outcomes of different importance in women with gestational diabetes. Whether this target can be extrapolated to women with pregestational diabetes or whether targets above or below this threshold offer a better benefit/risk balance remains unclear.