A staging approach combining fasting plasma glucose (FPG) and 1-hour plasma glucose (PG) levels showed stronger prediction of future type 2 diabetes mellitus (T2DM) than glycated hemoglobin (HbA1c)-based staging in middle-aged and older adults, according to findings published in Diabetologia.
The analysis included 1,174 adults from the Rio Grande do Sul center of the ELSA-Brasil cohort between 2017 and 2024, with a mean follow-up of 5.3 years. Participants were categorized using predefined stages of mild and moderate hyperglycemia based on combinations of FPG with either 1-hour PG or HbA1c levels. Insulin responsiveness was assessed using the insulin secretion-sensitivity index-2 (ISSI-2), while incident T2DM was determined using self-reported diagnoses and glucose measurements obtained during follow-up.
Findings
- The FPG/1-hour PG schema stratified participants into progressive metabolic stages associated with decreasing ISSI-2 levels and increasing frequency of high-risk complication profiles.
- Relative risk (RR) for incident T2DM increased progressively across stages, reaching 15.4 (95% CI 6.1-38.8) in Stage 3 in crude analyses.
- After adjustment, Stage 3 remained associated with substantially higher T2DM risk (RR 11.4; 95% CI 4.5-18.0).
- The FPG/1-hour PG staging approach achieved 89.1% sensitivity and 53.7% specificity for predicting incident T2DM.
- Applying a clinical risk score before laboratory testing improved specificity to 60.3% and reduced laboratory testing requirements by 27.1%.
- FPG/HbA1c staging approaches showed lower relative risks and weaker predictive performance than FPG/1-hour PG staging, although they outperformed conventional binary prediabetes classification.
The findings suggest that combining FPG with 1-hour PG measurements may improve identification of individuals at higher future risk for T2DM while reducing unnecessary laboratory testing when paired with a clinical risk score.
