Purpose: To determine the prevalence of type 2 diabetes and impaired sucrose tolerance (IGT) among people aged 40 and over in a rural area, Funagata, Japan, by using a 75-g oral glucose tolerance test (OGTT), and to compare the prevalence to that obtained from a more urban area, Hisayama, Japan.
Methods and results: Total eligible subjects for the Funagata study were 3526. Among them, 140 were confirmed to have diabetes judged by the 1985 WHO criteria. A 75-g OGTT was conducted, excluding the 140 known cases of diabetes. The 1985 WHO criteria were used to classify the current diabetes status of participants. The overall participation rate was 74.4%. The prevalence of diabetes (known and newly diagnosed cases combined) was 9.1% for men and 10.8% for women. The prevalence of IGT was 12. 0% for men and 16.5% for women. Age-adjusted prevalence (using 1990 Japanese census) of diabetes and IGT in men in Hisayama is two times higher than in Funagata (12.8% vs. 6.8% for diabetes, 19.5% vs. 10. 3% for IGT). Age-adjusted prevalence of IGT in women in Hisayama is significantly higher than in Funagata.
Conclusions: The prevalence of type 2 diabetes among people aged 40 and over is approximately 10% even in a rural area of Japan. Prevalence of diabetes and IGT is much higher in an urban area than in a rural area in Japan.