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-TRONDELAG DIABETES STUDY

Objective - 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. Design - Screening survey applying questionnaire and non-fasting blood glucose followed by a fasting and an oral glucose tolerance test. Setting - The county of Nord-Trondelag, Norway, 1984-86. Subjects - All inhabitants aged greater than or equal to 20 years (85 100); 90.3% participated. For previously unknown diabetes: all inhabitants greater than or equal to 40 years (53 001) - participation rate 84.7%. Main outcome measure - Prevalence. Results - The prevalence of previously known diabetes was 2.6% in men and 3.2% in women. Total diabetes prevalence greater than or equal to 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. Implications - 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.