Coronary heart disease mortality amongst non-insulin-dependent diabetic subjects in Iceland: the independent effect of diabetes. The Reykjavik Study 17-year follow up.

OBJECTIVES: The main aim of this study was to estimate the independent risk for coronary heart disease (CHD) death associated with non-insulin dependent (Type 2) diabetes (NIDDM) and effect on life expectancy. DESIGN AND SETTING: The Reykjavik Study is a prospective cardiovascular population study which started in 1967. A randomized selection procedure identified individuals for invitation to participate, based on their year and date of birth. Participants were examined in the years 1967-91 in one research clinic in Reykjavik. SUBJECTS AND METHODS: The population in this survey were Icelandic Caucasian males and females, born 1907-35 and therefore 34-79 years old when their examination was performed. Altogether 9139 males and 9773 females attended, and of those 267 males and 210 female were NIDDM as defined by a questionnaire or an oral glucose tolerance test. Other factors measured in the study included systolic and diastolic blood pressure, fasting total cholesterol, triglycerides, uric acid, smoking habits, height, and weight. The causes of death were determined by a review of all death certificates. Results. The relative risk of death from CHD (95% confidence limits), independently associated with NIDDM, was 2.0 (1.5-2.6) for males and 2.4 (1.6-3.6) for females. The relative risk of death from all causes was 1.9 (1.6-2.3) and 1.7 (1.3-2.1), respectively, for male and female diabetic patients. CONCLUSIONS: Non-insulin dependent diabetes mellitus carried twice the risk of CHD death in both sexes, independently of other risk factors. The diagnosis of NIDDM at the age 55 years reduced an individual's life expectancy by about five years, mostly because of increased CHD death rate.

Prevalence and incidence of NIDDM in Iceland: evidence for stable incidence among males and females 1967-1991--the Reykjavik Study.

This is the first large survey carried out in Iceland to estimate the prevalence and incidence of known and unknown non-insulin-dependent (Type 2) diabetes (NIDDM) among males and females, aged 34-79. The population in this survey was 9128 males and 9759 females born between 1907 and 1935 and examined in the prospective Reykjavik Study 1967-1991. Participants were invited from one to five times during the 24 years. The overall age-standardized prevalence (95% confidence limits) was 2.9% (2.5 to 3.3) for males and 2.1% (1.8 to 2.5) for females, aged 30-79, according to the European standard population. The overall annual age-standardized incidence rate per 100,000 was 377 (303 to 457) for males and 266 (212 to 320) for females, aged 35-74, standardized to the European population. Our study indicates that the prevalence of NIDDM is relatively low compared to other Nordic and western countries, and has not been increasing over the past 20 years. Furthermore, the incidence of NIDDM has not been changing during the past 20 years of follow-up among Icelandic males and females aged 34-79.