Objective: To describe the prevalence of previously diagnosed and undiagnosed diabetes and impaired glucose tolerance (IGT) by sex, marital status, employment, exercise behaviour, and body mass index (BMI), and to compare previously diagnosed and undiagnosed diabetic patients.
Design: A survey of the total 55-year-old population living in a Finnish city on 1 October 1990. All the participants who were not on antidiabetic medication were invited for an oral glucose tolerance test (OGTT).
Setting: Oulu, a city in northern Finland.
Subjects: 1,008 eligible subjects (456 men and 552 women), of whom 345 men (76%) and 435 women (79%) participated.
Main results: The prevalence of previously diagnosed diabetes was 6.1% in the men and 3.0% in the women and that of previously undiagnosed diabetes 4.5% of the men and 3.7% of the women. The prevalence of IGT was 28.6% in the men and 26.7% in the women. Diabetes was related to BMI, and previously undiagnosed diabetes was related to the amount of physical exercise in both sexes. One third of the undiagnosed diabetic men and half of the undiagnosed diabetic women were identified among the persons with marked obesity (BMI 30 kg/m2 or more). The group of previously diagnosed diabetic patients included a significantly greater proportion of retired people and people on sick leave than the group of undiagnosed diabetic persons.
Conclusions: Diabetes is common in middle-aged Finns. Undiagnosed diabetes was detected especially in persons with marked obesity who were not physically active.