Diabetes may impact on health-related quality of life (HRQOL). The aim of this population-based study was to confirm this influence. We examined 2135 residents aged > or =30 years in an entire community, who had no history of cancer or cardiovascular disease and did not require care for daily activity. The response rate was 87.8%. The status of diabetes, other chronic diseases and life practices were assessed by self-reported questionnaires, in which HRQOL was evaluated by the Japanese version SF-36, based on five sub-scales of the domain. Diabetes had been diagnosed in 165 (7.7%) of the study population. Comparison of data, adjusted for sex, age, living alone and employment status between non-diabetics and subjects with diabetes treated by pharmacological therapy had odds ratios (ORs) between the lowest quartiles of sub-scale scores of 1.90 for physical role, 2.51 for general health, and 1.79 for emotional role. The OR for lower general health was also increased in people using only lifestyle modification for treatment of diabetes. Although the OR for mental health was worse in the lifestyle modification group it was not increased in people with diabetes on pharmacological therapy. These associations remained almost unchanged after adjustment for the covariates. The sub-scales of physical and emotional roles and general health were decreased significantly in diabetics with duration of disease between 10 and 19 years or > or =20 years. Our study showed treatment of diabetes clearly influenced HRQOL, with this influence being dependent on the duration of diabetes and primarily affecting physical rather than mental health.