β-Cell function in postmenopausal women with isolated post-challenge hyperglycemia.

BACKGROUND

Isolated post-challenge hyperglycemia (IPH) is an early stage of type 2 diabetes mellitus (T2DM), with fasting glucose <126 mg/dL and 2-h glucose ≥200 mg/dL. Observations of insulin secretion profile in subjects with IPH may provide an insight into the pathogenesis of T2DM in older women.

METHODS

We recruited 555 naturally postmenopausal women without a history of T2DM to the present study. All participants received a 75-g oral glucose tolerance test to determine whether they had IPH. General linear models were used to compare differences in glucose metabolism among subjects.

RESULTS

Early phase insulin responses to oral glucose were significantly decreased in women with IPH versus those with impaired glucose tolerance (IGT) and normal glucose tolerance (geometric mean [95% confidence interval] insulinogenic index 61 [54-79] vs 90 [83-97] and 105 [96-116], respectively; P  < 0.0001). In addition, there were significant decreases in late-phase insulin release as metabolic status shifted from normal glucose tolerance to IGT to IPH. In the present cohort, the relative contribution of early insulin secretion to 2-h glucose was no longer significant ( P  = 0.15) after multiple factors, including indicators of insulin resistance and late-phase insulin release, were entered into the regression model simultaneously.

CONCLUSIONS

The results demonstrate that postmenopausal women with IPH are characterized by impaired β-cell function. There were significant decreases in early and late-phase insulin release as glucose intolerance escalated. Disturbance in β-cell function seems to be an important factor associated with early T2DM in postmenopausal women.