The One-Hour Oral Glucose Tolerance Test to Predict Glucose Intolerance Postpartum in Women With Prior Gestational Diabetes.

BACKGROUND

Women with prior gestational diabetes (GDM) are at higher risk of developing dysglycaemia postpartum. We evaluated whether the 1-h glucose on the postpartum OGTT predicts dysglycaemia and metabolic changes.

METHODS

Secondary analysis of a multicentre randomised controlled trial evaluating a mobile-based lifestyle intervention early postpartum in women with prediabetes after GDM (WHO 2013 criteria). Women were categorised by their 1-h glucose value at 3 months postpartum (baseline), using 8.6 mmol/L as the high-risk threshold following International Diabetes Federation criteria. A subgroup underwent a repeat OGTT at 12 months.

RESULTS

At 3 months postpartum, 28.0% (334/1193) had dysglycaemia based on the 2-h OGTT and 34.2% (408/1193) based on the 1-h glucose value. Women identified only by the 1-h glucose were less insulin resistant but showed similar β-cell dysfunction compared with those identified only by the 2-h OGTT. Among 166 women with baseline prediabetes defined by the 2-h OGTT, 63.9% (106) had 1-h glucose ≥ 8.6 mmol/L. At 1 year postpartum, women with baseline 1-h glucose ≥ 8.6 mmol/L accounted for all eight (7.3%) diagnoses of type 2 diabetes (p = 0.036), more dysglycaemia (61.5 vs. 40.4%, p = 0.010), greater β-cell impairment (lower ISSI-2, p = 0.001) and greater insulin resistance (lower Matsuda, p = 0.049) compared with those with 1-h glucose < 8.6 mmol/L.

CONCLUSION

In women with a recent history of GDM and subsequent prediabetes, a 1-h glucose value ≥ 8.6 mmol/L in early postpartum was associated with an increased risk for future type 2 diabetes, greater insulin resistance and impaired β-cell function, supporting its potential value as an early marker of metabolic risk.

TRIAL REGISTRATION: MELINDA Trial, NCT03559621.