Using fasting plasma glucose concentrations to screen for gestational diabetes mellitus: prospective population based study

Abstract Objective: To evaluate whether measuring fasting plasma glucose concentration is an easier screening procedure for gestational diabetes mellitus than the 1 hour 50 g glucose challenge test. Design: Prospective population based study. Setting: Outpatient clinic in a university hospital. Participants: 520 pregnant women (328 (63%) white, 99 (19%) Asian, 31 (6%) African, 62 (12%) others) with mean age 28.4 (SD 0.2; range 17-45) years. All underwent a glucose challenge test between the 24th and 28th gestational week, followed by a diagnostic 3 hour 100 g oral glucose tolerance test within one week. This was done irrespective of the result of the challenge test. Main outcome measure: Receiver operating curves were used to determine the best cut off values for screening with fasting plasma glucose concentrations. Results: Fasting plasma glucose concentration at a threshold value of 4.8 mmol/l and the glucose challenge test with a threshold value of 7.8 mmol/l yielded sensitivities of 81% and 59% respectively and specificities of 76% and 91% respectively. Measuring fasting plasma glucose concentration as a screening procedure required a diagnostic test in 30%, compared with 14% when the challenge test was used. Conclusions: Measuring fasting plasma glucose concentrations using a cut off value of ≥4.8 mmol/l is an easier screening procedure for gestational diabetes than the 50 g glucose challenge test and allows 70% of women to avoid the challenge test. Key messages Identifying women susceptible to gestational diabetes is particularly important not only to prevent perinatal morbidity but also to improve long term outcomes for the mother and her child Measuring fasting plasma glucose concentration is an easier screening procedure for gestational diabetes than the 1 hour 50 g glucose challenge test With a threshold value of 4.8 mmol/l it yields a sensitivity of 81% and a specificity of 76% Measuring fasting plasma glucose concentration allows 70% of women to avoid a glucose challenge test