The IDF Diabetes Atlas methodology for estimating global prevalence of hyperglycaemia in pregnancy

Introduction: Hyperglycaemia is one of the most prevalent metabolic disorders occurring during pregnancy. Limited data are available on the global prevalence of hyperglycaemia in pregnancy. The International Diabetes Federation (IDF) has developed a methodology for generating estimates of the prevalence of hyperglycaemia in pregnancy, including hyperglycaemia first detected in pregnancy and live births to women with known diabetes, among women of childbearing age (20-49 years). Methods: A systematic review of the literature for studies reporting the prevalence of gestational diabetes was conducted. Studies were evaluated and scored to favour those that were representative of a large population, conducted recently, reported age-specific estimates, and case identification was based on blood test. Age-specific prevalence data from studies were entered to produce estimates for five-year age groups using logistic regression to smooth curves, with age as the independent variable. The derived age-specific prevalence was adjusted for differences in diagnostic criteria in the underlying data. Cases of hyperglycaemia in pregnancy were derived from age-specific estimates of fertility and age-specific population estimates. Country-specific estimates were generated for countries with available data. Regional and global estimates were generated based on aggregation and extrapolation for 219 countries and territories. Available fertility rates and diabetes prevalence estimates were used to estimate the proportion of hyperglycaemia in pregnancy that may be due to total diabetes in pregnancy - pregnancy in women with known diabetes and diabetes first detected in pregnancy. Results: The literature review identified 199 studies that were eligible for characterisation and selection. After scoring and exclusion requirements, 46 studies were selected representing 34 countries. More than 50% of selected studies came from Europe and North America and Caribbean. The smallest number of identified studies came from sub-Saharan Africa. The majority of studies were for high-income countries, although low- and middle-income countries were also represented. Conclusion: Prevalence estimates of hyperglycaemia in pregnancy are sensitive to the data from which they are derived. The IDF methodology is a transparent, reproducible, and modifiable method for estimating the burden of hyperglycaemia in pregnancy. More data are needed, in particular from developing countries, to strengthen the methodology. (C) 2013 Elsevier Ireland Ltd. All rights reserved.