FASTING PLASMA-GLUCOSE AS A DIAGNOSTIC INDICATOR OF DIABETES-MELLITUS

Among 233 patients referred for glucose tolerance test (GTT), 36.4% of 129 non-pregnant subjects were classified as diabetic, compared with only 2.9% of 104 pregnant subjects. Preliminary screening using a fast ing plasma glucose upper cut-off of 7.0 mmol/l, above which the subjec t was classified as diabetic and a lower one of 4.4 mmol/l, below whic h he or she was considered normal, would have eliminated; the need for 30% of GTTs and positively identified 60% of the diabetics in the non -pregnant group, Only one patient would have been significantly miscla ssified, possibly owing to inadequate fasting. However, little benefit would result from applying an upper cut-off to low-prevalence populat ions such as the pregnant group. Like other recent surveys, this study suggests that World Health Organisation diagnostic figures for fastin g plasma glucose could be revised downwards to 7.0 mmol/l. Conversely, to be fairly certain that an individual is not diabetic, fasting plas ma glucose must be below about 4.4 mmol/l.