Progression to impaired glucose regulation and diabetes in the population-based Inter99 study

The purpose of this study was to estimate the progression rates to impaired glucose regulation (impaired fasting glucose or impaired glucose tolerance) and diabetes in the Danish population-based Inter99 study and in a high-risk subpopulation, separately.

From a population-based primary prevention study, the Inter99 study, 4,615 individuals without diabetes at baseline and with relevant follow-up data were divided into a low- and a high-risk group based on a risk estimate of ischemic heart disease or the presence of risk factors (smoking, hypertension, hypercholesterolemia, obesity, or impaired glucose tolerance). High-risk individuals (57.1%) were examined with an oral glucose tolerance test at 1 and 3 years, and all of the participants were reexamined at the 5-year follow-up. Person-years at risk were calculated. Progression rates to impaired glucose regulation and diabetes were estimated directly from baseline to the 5-year follow-up for all the participants and from baseline through the 1- and 3- to 5-year follow-up examinations for the high-risk individuals, separately.

In the combined low- and high-risk group, 2.1 individuals per 100 person-years progressed from normal glucose tolerance (NGT) to impaired glucose regulation or diabetes. Among high-risk individuals, 5.8 per 100 person-years with NGT progressed to impaired glucose regulation or diabetes, and 4.9 per 100 person-years progressed from impaired glucose regulation to diabetes.

Progression rates to impaired glucose regulation using the current World Health Organization classification criteria were calculated for the first time in a large European population-based study. The progression rates to diabetes show the same pattern as seen in the few similar European studies.