Pospartum Assessment of Insulin Secretion and Sensitivity in Women with Gestational Diabetes Mellitus (GDM)

Hong, Eun Soon; Lee, Hye Jin; Hong, Young Sun; Sung, Eon Ah; Jang, Yeon Jin

Abstract

BACKGROUND: Gestational diabetes mellitus (GDM) affects 2~4% of all pregnant women. Women with a history of GDM are at high risk of developing type 2 DM, in the future; with a cumulative incidence is 40~60%. Therefore, the assessment of insulin secretion and sensitivity in women with a history of GDM should help in the elucidation of some of the underlying defects of insulin secretion or action in the evolution of type 2 DM. This study was performed to evaluate the characteristics of insulin secretory capacity and sensitivity in women with gestational diabetes following child birth.
METHODS
Oral glucose tolerance tests were carried out at 6~8 weeks postpartum in 22 women with a history of GDM, and 20 age and weight matched non- pregnant controls. Frequently sampled intravenous glucose tolerance test (FSIGT) were done at 10~14 weeks postpartm, and insulin secretion was measured as the acute insulin response to glucose (AIRg) and insulin sensitivity as minimal model derived sensitivity index (SI). AIRg*SI was used as an index for beta-cell function because AIRg can be modulated by SI.
RESULTS
According to the results of OGTT, the subjects with a history of GDM were classified into 2 groups, one of normal glucose tolerance (postpartum-NGT) (n=11) and the other of an impaired glucose tolerance (postpartum-IGT)(n=11). There were no significant differences in WHR (waist to hip ratio), blood pressure, and serum lipid concentrations among the controls, postpartum-NGT and postpartum-IGT group. The fasting glucose level was significantly higher in the postpartum-IGT group compared to the postpartum-NGT and control groups (p<0.05). The fasting serum insulin level was significantly lower in the postpartum-NGT and -IGT groups than in the control group (p<0.05). The AIRg and AIRg*SI were significantly lower in the postpartum-NGT and -IGT groups compared to the control group (p<0.05), however the SI was lower in the postpartum-NGT and -IGT groups compared to the control group, but the difference did not reach statistical significance. The percentage of parental with history of type 2 diabetes was significantly greater in the postpartum-IGT group compared to the postpartum-NGT group (p<0.05). No significant predictive factors for subsequent IGT were found inform a logistic regression analysis.
CONCLUSION
The insulin secretory capacity of women previously having suffered GDM was impaired, even though their glucose tolerance was restored to normal following child birth. Our results suggest that impaired insulin secretion may be a major path-ophysiological factor in the development of type 2 DM in women with a previous history of GDM.