Objectives To determine the optimal HbA1c test interval strategy to detect new type 2 diabetes mellitus (T2DM) cases among healthy population, stratified by age and body mass index (BMI).

Methods Markov models were built to study the optimal screening interval for new cases of T2DM among each age- and BMI-stratified health population. Age was stratified into 30–44, 45–59, and 60–74 year age groups and BMI was also stratified into underweight (<18.5 kg/m²), normal (18.5–25 kg/m²), overweight (25–30 kg/m²) and obese (<30 kg/m²). In each model, different HbA1c test intervals were compared to evaluate costs per quality-adjusted life year (QALY) and the incremental cost-effectiveness ratio (ICER). We compared annual intervals (current Japanese strategy), every three years (US and UK recommendations) and intervals tailored for each risk stratification group, focusing on HbA1c test characteristics of signal (true change) and noise (error), which were reported in the previous study. All model parameters including screening and treatment costs, complication and mortality rates and utilities were also drawn from published studies. The willingness-to-pay threshold in cost-effectiveness analysis was set to US $50,000/QALY.

Results The HbA1c test interval to detect T2DM in a healthy population varies by age and BMI.Three year interval were cost-effective in obese groups at all ages; 30–44: $12,575/QALY, 45–59: $25,843/QALY, 60–74: $36,366/QALY compared to annual screening interval. Three year interval were also cost effective in the 60–74 age groups; underweight: $42,777/QALY, normal: $39,448/QALY, overweight: $27,436/QALY and overweight in the 45–59 age group; $23,987/QALY. In other groups, the screening interval to detect T2DM were found to be longer than three years as previous study reported. Annual screening was too expensive and dominated in many groups with low BMI and in younger age groups. Based on probability distribution of ICER, QALY does not show much difference among any groups.

Conclusions Annual screening to detect T2DM was not cost effectiveness and should not apply for any population. The three-year screening interval were optimal among all elderly population, obese group at all ages and overweight group among the 45–59 years old. Among low BMI and in younger age groups, optimal HbA1c test interval can be longer than three years.