Hyperglycemia as a risk factor of mortality in a middle-aged Finnish population

In 1990-1992, a population-based study was carried out in the city of Oulu in northern Finland, to assess the prevalence of diabetes mellitus (DM) and impaired glucose tolerance (IGT) in a middle-aged population. We report the mortality of the study population until 31 December 1998. Altogether 831 subjects (82%) (369 men) participated in the baseline examinations, in which the prognostic risk factors were determined. Special attention was given to the effect of hyperglycemia on mortality. The WHO 1985, ADA 1997 and WHO 1999 criteria for diabetes, IGT and impaired fasting glucose (IFG) were used. Forty-one subjects (32 men) died during the average follow-up of 6.7 years, and the mortality rate was hence 7.7/1000 person-years. The results suggest that both fasting and post-load hyperglycemia are important predictors of mortality. Estimated by the Cox proportional hazards regression, the unadjusted hazard ratio (HR) for death was 2.5 (95% CI 0.9-6.6) in the subjects classified as diabetic according to the WHO 1999 criteria compared to normoglycemic subjects. The corresponding HR of the subjects with IFG was 2.5 (95% CI 0.7-8.8) and that of the subjects with IGT 1.5 (0.6-3.7). In addition, a high mortality was predicted by smoking (HR 4.2, 95% CI 2.0-8.8), male gender (HR 3.5, 95% CI 1.6-7.9) and hypertension (HR 2.3, 95% CI 1.1-5.1).