Background: The prevalence of type 2 diabetes mellitus (T2DM) is increasing worldwide. More knowledge on the proportion of undiagnosed diabetes in the population may be useful for future prevention strategies. Accordingly; we aimed to report prevalence of known and unknown T2DM, as well as risk factors associated with unknown T2DM, in a middle-aged Norwegian population.
Methods: All women and men born in 1950, residing in Akershus county, Norway, were invited in the Akershus Cardiac Examination (ACE) 1950 study. All participants underwent a clinical examination including fasting blood glucose (FBG) and HbA1c. Known T2DM was defined as self-reported history of T2DM or daily use of antidiabetic drugs, and unknown T2DM was defined as the absence of any of these combined with FBG ≥7.0 mmol/L and HbA1c ≥6.5%. Risk factors associated with unknown T2DM were assessed by multivariate logistic regression.
Results: A total of 3706 among 5827 eligible subjects were included. Mean age was 63.9±0.7 years, 48.8% were women. Known diabetes was reported in 7.2% (9.6% men, 4.6% women; p<0.001). Unknown T2DM was found in 1.3% (1.9% men, 0.7% women; p=0.001), and the total prevalence of diabetes was 8.6% (11.6% in men, 5.4% women; p<0.001). Variables associated with unknown T2DM are presented in Table.
Conclusion: In a contemporary Norwegian population cohort aged 64 years, we identified a considerable proportion of previously unknown T2DM in both sexes, but particularly in men. Elevated BMI, systolic blood pressure, triglycerides, low HDL-cholesterol and a family history of diabetes were associated with unknown T2DM.