PREVALENCE OF RETINOPATHY IN PEOPLE WITH DIABETES, IMPAIRED GLUCOSE-TOLERANCE, AND NORMAL GLUCOSE-TOLERANCE

OBJECTIVE - Recently, an international expert committee published new revised criteria for diagnosing diabetes. According to the new criteri a, the 2-h glucose level for diabetes in the oral glucose tolerance te st (OGTT) is the same as in the previous World Health Organization cri teria, but the cut point for the fasting blood glucose level has been lowered to be equivalent to the 2-h OGTT level. Measurement of the fas ting blood glucose level is preferred to the 2-h OGTT glucose level. T he ability of the new cut point for fasting blood glucose to discrimin ate between those at a high and a low risk for retinopathy was tested in a population-based study. RESEARCH DESIGN AND METHODS - The populat ion consisted of all the 1,008 subjects (456 men) born in 1935 and liv ing in a Finnish city. A screening for type 2 diabetes was carried out in the first phase. All participants who were not on antidiabetic med ication were invited for an OGTT in the second phase. A fasting blood glucose value was measured from the diabetic subjects on antidiabetic medication. In addition, measurements of serum cholesterol, HDL choles terol, and triglycerides were made, and fundus photographs were taken. Altogether 831 subjects (368 men) (82%) participated and constitute t he eligible study population for the present analyses. Fundus photogra phs were available for 790 subjects (347 men) (95%). RESULTS - There w ere 28 subjects (3.5%) who had mild retinopathic changes in the fundus photographs. Retinopathic changes were associated with higher fasting blood glucose levels, but not with any of the other background factor s. The prevalence of retinopathy was 10.2% (95% CI 4.8-18.5) in subjec ts with a fasting blood glucose of greater than or equal to 6.1 mmol/l , while it was 2.6%, (1.5-4.0) in those with a lower fasting blood glu cose level. In the former group, a majority (seven of nine) of the sub jects with retinopathy were previously diagnosed diabetic patients. So me cases of retinopathy were found regardless the level of glycemia, a nd measurement of the 2-h OGTT glucose levels did not increase informa tion. CONCLUSIONS - The results of this population study give support to the use of fasting blood glucose levels in diagnosing type 2 diabet es. The lower limit of the highest decile of the fasting glucose level was 6.1 mmol/l, and it discriminated subjects at a high risk for reti nopathy from those at a low risk. Because of the limited number of sub jects with retinopathy in this study. the level of hyperglycemia assoc iated with retinopathy cannot be estimated accurately.