Diabetes risk after a normal oral glucose tolerance test during pregnancy

INTRODUCTIONOur aim was to conduct a follow-up of a cohort of women screened for GDM with a normal oral glucose tolerance test (OGTT) during pregnancy to investigate the incidence and time of diagnosis of manifest diabetes mellitus and identify risk factors for subsequent development of diabetes. METHODSThis was a follow-up study of a cohort with normal and borderline OGTT in 1991/1992. Among the original 352 women, only five were lost to follow-up. RESULTSIn total, 64 women (18%) had manifest diabetes. Their median age was 57 years after 28 years of follow-up. This amounts to three times the expected rate compared with the background population. The rate of manifest diabetes rises 10-20 years after pregnancy and after the age of 40 years. A normal fasting glucose and also a borderline fasting glucose at OGTT during pregnancy were associated with an increased risk of manifest diabetes (p less-than 0.001), also after adjustment for age, Body Mass Index, non-Danish origin and smoking during pregnancy (p less-than 0.002). CONCLUSIONThe incidence of diabetes is higher in women with various risk factors for DM and a previously normal OGTT in pregnancy than in the background population. Our results are useful in identifying the time during which women may benefit from effective implementation of evidence-based treatment to postpone and avert manifest DM, even though they had a normal OGTT during pregnancy. FUNDINGnone. TRIAL REGISTRATIONThe trial was registered with the the Regional Ethics Committee and the Data Protection Agency, nos. 2014-41-3433, 1-16-02-824-17 (under running permission no. 621549), 1-16-02-825-17, and 1-16-02-180-17, all under the cover of data handling agreement no. 509 with the Danish Health Authority.