Intermittent Metformin May Be as Effective as Continuous Therapy After Gestational Diabetes: Study
China: Researchers have found in a randomized controlled trial of 334 postpartum women with prediabetes and a history of gestational diabetes that intermittent metformin combined with lifestyle modification was non-inferior to continuous metformin in preventing progression to type 2 diabetes over 3 years. Diabetes incidence was similar with continuous and intermittent therapy (11.1% vs 11.5%), suggesting that an intermittent regimen may provide comparable preventive efficacy while potentially reducing treatment burden.
The findings were published in BMC Medicine by Fenghua Lai, Department of Endocrinology, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China, and colleagues.
Women who develop gestational diabetes mellitus (GDM) are at substantially increased risk of progressing to type 2 diabetes after pregnancy, particularly if they develop prediabetes during the postpartum period. While metformin is an established preventive therapy, it remains unclear whether taking the drug only when blood glucose levels worsen could be as effective as continuous treatment. To address this question, researchers conducted a randomized, open-label, non-inferiority trial across three centers in China.
The trial enrolled women aged 18–45 years with prior gestational diabetes and prediabetes diagnosed 4–12 weeks postpartum. Participants were randomized to lifestyle intervention plus either intermittent or continuous metformin. In both groups, metformin was initiated only if lifestyle measures failed to maintain normal glucose levels. Continuous therapy was maintained once started, whereas intermittent therapy was stopped after glucose normalization and restarted only if needed.
Overall, 376 women were randomized, and 334 completed the primary analysis after three years. The primary outcome was the incidence of newly diagnosed type 2 diabetes.
Key findings
- After three years, type 2 diabetes developed in 11.5% of women receiving intermittent metformin and 11.1% receiving continuous therapy.
- The absolute difference in diabetes incidence was 0.4 percentage points, meeting the predefined criterion for non-inferiority.
- Rates of prediabetes remission, changes in body weight, body mass index, waist circumference, fasting plasma glucose, two-hour plasma glucose, and HbA1c were comparable between the two groups.
- Women receiving continuous metformin had a significantly higher rate of metformin-associated vitamin B12 deficiency than those on intermittent therapy (13.5% vs 3.7%).
The researchers found that intermittent metformin provided diabetes prevention comparable to continuous therapy while reducing prolonged medication exposure and the risk of metformin-related vitamin B12 deficiency.
The authors acknowledged the study's relatively wide non-inferiority margin and the small number of diabetes events. They concluded that although intermittent metformin plus lifestyle intervention appears to be a promising alternative to continuous therapy in postpartum women with prediabetes after gestational diabetes, larger studies with stricter non-inferiority criteria are needed to confirm these findings.
Reference:
Lai, F., Pei, L., Xu, C. et al. The efficacy of intermittent metformin plus lifestyle intervention for diabetes prevention in women with prediabetes and prior gestational diabetes: a randomized clinical, non-inferiority trial. BMC Med (2026). https://doi.org/10.1186/s12916-026-05059-5
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