Screening healthy people for diabetes: is it worthwhile?

BACKGROUND

The objectives of this study were (1) to estimate the prevalence of previously unknown diabetes mellitus in an apparently healthy population aged 40 years and older, (2) to estimate the ratio of known to unknown diabetics, and (3) from this information, to estimate the true prevalence of diabetes.

METHODS

A one in five random sample of healthy patients aged 40 years and older attending six rural family physician offices had their fasting plasma glucose (FPG) level tested with a reflectance glucometer. If the FPG was greater than or equal to 7.8 mmol/L (140.5 mg/dL), a second FPG test was done on a later day.

RESULTS

The sample of 1264 patients contained 139 known patients with diabetes. Of the remaining 1125 patients, 936 (83%) were tested. Twenty-three patients had an elevated FPG level on the first test, but only nine of them had an elevated FPG level on the second test. One new patient with diabetes was found for each 15 patients already diagnosed; thus, the prevalence of unknown diabetes in the study population was 0.7%. As a result of this survey, the estimated prevalence of diabetes in the population age 40 years and older rose from 11.0% to 11.7%, and the estimated prevalence for the entire population rose from 4.4% to 4.6%.

CONCLUSIONS

Routine screening for diabetes mellitus in otherwise healthy patients aged 40 years and older is not worthwhile. Such screening should be restricted to high-risk groups.