TOPLINE

Gradual annual BMI gain over time was associated with risk for prediabetes in women of reproductive age.

METHODOLOGY

• Researchers conducted a retrospective cohort study using data from annual health checkups among women of reproductive age at four centers in Japan between 2015 and 2024 to assess whether annual BMI trajectories were associated with subsequent incident prediabetes.
• The analysis included 2271 women (mean age, 34.6 years) with normoglycemia (A1c levels < 5.7%) and without diabetes during an initial period (2015-2017).
• A change in annual BMI during this period was calculated for each woman and categorized into four groups according to BMI gains (loss, stable, moderate, and highest); A1c levels were also measured during annual visits.
• Incident prediabetes was defined as A1c levels reaching 5.7%-6.4% after 2017, with a median follow-up duration of 7 years.

TAKEAWAY

• Overall, 15.2% developed prediabetes. Each 1-year increase in age and each 1-unit higher BMI were associated with a higher risk for incident prediabetes in the multivariable Cox models.
• Every 0.1 increase in BMI per year during the landmark period was associated with an increased risk for incident prediabetes by 4% (hazard ratio, [HR], 1.04; P < .001).
• A1c levels at baseline were also associated with the risk for incident prediabetes (HR per 0.1% increment, 1.69; 95% CI, 1.58-1.81).
• Among women with a BMI of 18.5-22.9 at baseline, those with the highest BMI gains of at least 0.6 per year had a prediabetes rate of 22.5%, and among women with BMI ≥ 23.0 at baseline, those with the highest annual BMI gain had a prediabetes rate of 33.7%.

IN PRACTICE

“Because BMI and A1c are already measured in many occupational and community screening programs, incorporating longitudinal BMI trajectory in addition to single BMI thresholds may help identify individuals at elevated metabolic risk before overt glycemic deterioration occurs,” the researchers wrote.

SOURCE

The study was led by Sho Tano, MD, PhD, of the Department of Obstetrics and Gynecology at the Nagoya University Graduate School of Medicine in Nagoya, Japan. It was published online on July 26, 2026, in the American Journal of Preventive Medicine.

LIMITATIONS

BMI was used as a proxy for body fat, but the study did not include waist measurements, body composition data, or family history.

DISCLOSURES

The research was supported by the Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research. The authors declared having no conflicts of interest.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.