Does poor health insurance coverage contribute to increased microvascular complications (nephropathy and retinopathy) in Mexican Americans with non-insulin-dependent diabetes? Mexican-American subjects with diabetes were identified in a population-based cardiovascular risk factor survey, the San Antonio Heart Study. Retinopathy, nephropathy, source of health care, and type and extent of health insurance coverage were assessed in a special diabetes complications exam. Among Mexican-American subjects with non-insulin-dependent diabetes diagnosed prior to their participation in the survey (n = 255), 26% (n = 67) lacked any type of health insurance, and 28% relied on county- or federal-funded clinics rather than private doctors as their primary source of care. Among those with health insurance (188 of 255), only 68% (127 of 188) or 24% of the total sample had private health insurance, and, of those with private insurance, 48% (35 of 73) received reimbursement for outpatient doctor visits and 57% for outpatient medications. Microvascular complications were more common among those who received their health care from a clinic versus a private doctor, and among those who lacked health insurance coverage for outpatient doctor visits and medications. Thus, poor health insurance coverage in the outpatient setting correlates with higher rates of microvascular complications among Mexican Americans with non-insulin-dependent diabetes mellitus.