Objective To investigate the process quality of diabetes care provided to patients under universal health insurance coverage.

Research design and methods Using claim data for 570 363 beneficiaries aged 20–69 years who were covered by Health Insurance Societies between April 2010 and March 2012, we identified patients with type 2 diabetes who made follow-up visits at least every 3 months in the first year (subject-identification year). We assessed patient adherence to follow-up visits in the second year (quality-reporting year), calculated the proportion of patients that completed routine examinations for glycemic control and complications, and evaluated associations between characteristics of patients and quality indicators using multivariable logistic regression models.

Results We identified 12 909 patients with diabetes; in the subject-identification year, 1415 (11.0%) had prescriptions for insulin injections, 6049 (46.9%) had prescriptions for oral antihyperglycemic agents, and 5445 (42.2%) had no diabetes-related prescriptions. Among patients using medication, 474 (6.4%) dropped out in the quality-reporting year. The adjusted percentages of quality indicators among patients using oral antihyperglycemic agents were 95.8% for glycated hemoglobin, 35.6% for eye examinations, 15.4% for urine microalbumin excretion, and 90.6% for serum lipids; the percentages among patients taking insulin were the same or higher. Annual testing for glycated hemoglobin was less frequent in patients aged 40–49 years than in patients aged 60–69 years (OR 0.77; 95% CI 0.66 to 0.91). Fewer men than women (OR 0.59; 95% CI 0.54 to 0.64), and fewer patients aged 40–49 years than those aged 60–69 years (OR 0.56; 95% CI 0.50 to 0.63) tended to complete routine eye examinations.

Conclusions Screening for retinopathy and nephropathy was less frequent than required despite favorable conditions for access to healthcare in Japan. Suboptimal quality of care appeared to depend on provider factors as well as patient factors, such as limited access to retinopathy prevention among working-age men with diabetes.