Gestational diabetes mellitus – prevalence in southern Sweden and risk factors for subsequent diabetes

Background: Gestational diabetes mellitus (GDM) is associated with risks during pregnancy, during delivery, and in later life with a substantial risk of subsequent diabetes. The worldwide prevalence of GDM is increasing, but varies with differences in diagnostic methods and population characteristics.

Results: Capillary glucose concentrations were found to be higher than venous glucose concentrations during oral glucose tolerance test (OGTT) after pregnancy (n = 55). Equivalence values for capillary glucose concentrations tended to be higher than those proposed by the WHO, but diagnostic disagreements mainly occurred close to the diagnostic cut-off limits.

In southern Sweden, defining GDM as a 2-h capillary plasma glucose concentration of ≥ 10.0 mmol/L during a universal 75-g OGTT, there was a 35% increase in GDM prevalence (p < 0.001) from 2003 (1.9%) to 2012 (2.6%) when assessed in a log-linear Poisson model during a period with stable diagnostic procedures.

1–2 years after pregnancy with GDM (n = 456), the increased frequency of diabetes in non-European women (17% vs. 4% in European women, p < 0.001) was associated with increased insulin resistance―related to higher body mass index (BMI) in Arab women, and higher insulin resistance relative to BMI in Asian women.

In logistic regression analysis, diabetes 5 years after GDM was associated with higher BMI at follow-up, non-European ethnicity, and higher OGTT 2-h glucose concentration in pregnancy (p < 0.0001). A prediction model based on these variables resulting in 86% correct classifications (n = 200), with an area under the receiver-operating characteristic curve of 0.91 (95% CI 0.86–0.95), was used in a function-sheet line diagram illustrating the individual effect of weight on diabetes risk.

Conclusions: Interconversion of results from capillary sampling and venous sampling is associated with uncertainty, but it may be suitable when translating results on a group basis. The prevalence of GDM in southern Sweden was 2.6% in 2012, with an upward trend. In women with GDM, insulin resistance was associated with subsequent diabetes, predicted by BMI, non-European ethnicity, and glucose tolerance during pregnancy.