Prevalence of known and previously unknown diabetes mellitus and impaired glucose tolerance in an adult Norwegian population. Indications of an increasing diabetes prevalence. The Nord-Trøndelag Diabetes Study.

Abstract

To establish the prevalence of known and undiagnosed diabetes mellitus and impaired glucose tolerance in a representative Norwegian adult population according to the 1980 World Health Organization Expert Committee diagnostic criteria. Screening survey applying questionnaire and non-fasting blood glucose followed by a fasting and an oral glucose tolerance test. The county of Nord-Trøndelag, Norway, 1984-86. All inhabitants aged > or = 20 years (85,100); 90.3% participated. For previously unknown diabetes: all inhabitants > or = 40 years (53,001)--participation rate 84.7%. Prevalence. The prevalence of previously known diabetes was 2.6% in men and 3.2% in women. Total diabetes prevalence > or = 40 years was 4.8% in men and 5.6% in women. The prevalence increased continuously with age until 90 years. One patient in five was previously undiagnosed. Impaired glucose tolerance in those with an abnormal non-fasting value was rare; only 0.9% in men and 0.2% in women. The prevalence of known diabetes was three times higher than 20-30 years ago and four times higher than 50 years ago. Except for known diabetes in the very old the prevalence corresponded well with recent Nordic studies. The present diabetes prevalence was so high that interested general practitioners will get sufficient experience in follow-up of diabetic patients to facilitate a good quality of the care.