Women with normal glucose tolerance and a history of gestational diabetes show significant impairment of β-cell function at normal insulin sensitivity

Abstract

Objective: Although the nature of gestational diabetes mellitus (GDM) remains unclear, the condition is thought to be related primarily to insulin resistance, overweight and obesity. Most studies include women with a history of GDM and later carbohydrate metabolism abnormalities, while reports of women with previous GDM and subsequent normoglycaemia are scarce. The aim of this study was to assess insulin resistance and β-cell function in normoglycaemic women with a history of GDM.

Materials and methods: The study group included 199 women, aged 38.4±6.6 years, diagnosed with GDM within the last 5-12 years [GDM(+)] and a control group of 50 comparable women in whom GDM was excluded [GDM(-)], according to WHO criteria. Blood glucose and insulin levels were measured at the beginning (fasting) and at 60 and 120min of oral glucose tolerance tests. Indices of insulin resistance (HOMA-IR), insulin sensitivity (HOMA-S%) and β-cell function (HOMA-B%) were calculated.

Results: Normoglycaemia was observed in 57% of GDM(+) and 88% of GDM(-) women (P=0.0003). Diabetes was diagnosed in 13 (6.5%) GDM(+) women and in none of the GDM(-) women. Comparison of 113 normoglycaemic GDM(+) and 44 normoglycaemic GDM(-) women revealed significantly impaired β-cell function (HOMA-B%: 131.1±51.1 vs 144.7±47.1, respectively; P=0.038) with similar normal body mass index (BMI) and no differences in HOMA-IR and HOMA-S%.

Conclusion: In this study, more than half of the GDM(+) women were presented with normal glucose tolerance. However, despite normoglycaemia, women with a history of GDM were characterized by significantly impaired insulin secretion, but no signs of increased insulin resistance.