A 1-hour glucose value greater than equal to 8.6 mmol/L during OGTT in early postpartum is a useful marker of identifying women at high risk of future type 2 diabetes and metabolic dysfunction after gestational diabetes (GDM). These findings were published in the June 2026 issue of the journal Diabetes, Obesity and Metabolism (1).

A team of Belgian researchers investigated whether the 1-hour glucose value during a postpartum oral glucose tolerance test (OGTT) could predict future glucose intolerance and metabolic abnormalities in women with a previous history of gestational diabetes mellitus (GDM). For this they conducted a secondary analysis of a multicenter randomized-controlled trial assessing a mobile-based lifestyle intervention in women with glucose intolerance after gestational diabetes.

Participants were classified according to their 1-hour glucose level measured three months postpartum (baseline), with 8.6 mmol/L (155 mg/dL) as the cutoff for high metabolic risk. A subgroup was re-tested one year postpartum.

Among the 1193 participants, dysglycemia was identified in 28% using the conventional 2-hour OGTT value, whereas 34.2% were identified using the 1-hour glucose value. Women identified only through elevated 1-hour glucose levels had less insulin resistance but showed pancreatic beta-cell dysfunction that was similar to those detected by the standard 2-hour test. Among 166 women with baseline prediabetes defined by the 2-h OGTT, 63.9% (106) had 1-h glucose greater than equal to 8.6 mmol/L.

Women with baseline 1-hour glucose levels greater than equal to 8.6 mmol/L at 1 year postpartum demonstrated significantly worse metabolic outcomes, including higher rates of dysglycemia (61.5 vs. 40.4%), greater insulin resistance (lower Matsuda), reduced beta-cell function (lower ISSI-2), and all eight cases (7.3%) of type 2 diabetes.

The study thus suggests that incorporating the 1-hour glucose value into early postpartum screening may serve as an early predictor of future metabolic risk in women with prior gestational diabetes. It may be a more effective postpartum screening approach by enhancing early identification of women at risk of developing diabetes or prediabetes following hyperglycemia during pregnancy.

The International Diabetes Federation (IDF) recommends the 1-hour post-load plasma glucose (1-h PG) test as a more sensitive and practical method to screen for intermediate hyperglycemia, or prediabetes, and type 2 diabetes in those at risk. It recommends the cut offs of 155 mg/dL (8.6 mmol/L) for intermediate hyperglycemia and 209 mg/dL (11.6 mmol/L) for type 2 diabetes (2).

References

1.    Bochanen N, et al. The one-hour oral glucose tolerance test to predict glucose intolerance postpartum in women with prior gestational diabetes. Diabetes Obes Metab. 2026 Jun;28(6):4619-4629. doi: 10.1111/dom.70634.

2.    IDF News. Available at: https://idf.org/news-and-resources/news/idf-position-statement-1-hour-pg-test/. Dated March 12, 2024. Accessed on May 28, 2026.