Screening for impaired glucose tolerance. Results from a population-based study in 21,057 individuals

To study the distribution of fasting plasma glucose and impaired glucose tolerance (IGT) in a large general population and explore their possible implications for large-scale screening. The study focuses especially on the relation to age, obesity, and heredity background of diabetes.

A total of 21,057 men and women aged 30-60 years were used for this cross-sectional study. Individuals with known diabetes and individuals with a fasting plasma glucose > or = 7 mmol/l were excluded. A physical examination, including blood sampling and an oral glucose tolerance test, was conducted.

The relative risk for IGT increased more than fourfold among obese subjects compared with normal-weight subjects, yet only 25% of IGT subjects were obese. Similarly, IGT subjects more frequently reported having first-degree relatives with diabetes than did subjects with normal glucose tolerance. Nonetheless, > 70% of IGT subjects reported no heredity background of diabetes. Subjects with IGT showed higher mean values of BMI, blood pressure, and triglycerides. Only 13% of the men and 19% of the women having impaired fasting glucose (IFG) fulfilled the criteria of IGT.

The present study shows that a high-risk screening strategy for IGT targeted solely toward subjects with obesity and/or heredity background of diabetes will fail to detect the majority of subjects with IGT in the general population. The new concept of IFG may not replace the concept of IGT as a risk marker for worsening to diabetes.