Of 1324 women diagnosed with gestational diabetes mellitus (GDM) in Sweden, 25% reported >10 years after the delivery that they had developed diabetes mellitus. We assessed the long-term risk of all glucose metabolic abnormalities in a subgroup of these women. Women (n = 51) previously diagnosed with GDM by capillary blood glucose ≥9.0 mmol/L (≈plasma glucose ≥10.0 mmol/L) after a 2 h 75 g oral glucose tolerance test (OGTT) were included. All underwent a clinical and biochemical evaluation, including a second 2 h 75 g OGTT. Individuals with known type 1 diabetes were excluded. At the follow-up, 12/51 (24%) reported previously diagnosed type 2 diabetes. Another four cases were diagnosed after the second OGTT, increasing the prevalence to 16/51 cases (31%). Impaired fasting plasma glucose (IFG) was diagnosed in 13/51 women and impaired glucose tolerance (IGT) in 10/51 women, leaving only 12 women (24%) with normal glucose tolerance. In addition, 2/51 women had high levels of glutamic acid decarboxylase (GAD) antibodies; of these, one woman classified as type 2 diabetes was reclassified as type 1 diabetes, and the second GAD-positive woman was diagnosed with IGT. Of the women diagnosed with GDM by a 2 h 75 g OGTT, a large proportion had impaired glucose metabolism a decade later, including type 1 and type 2 diabetes.
Keywords: C-peptide; OGTT; autoimmunity; fasting glucose; gestational diabetes mellitus; impaired fasting glucose; impaired glucose tolerance; insulin resistance; maternal obesity; proinsulin.