OBJECTIVE -To determine the effect of lowering the fasting plasma glucose (FPG) criterion for impaired fasting glucose (IFG) on the prevalence of IFG, the risks of diabetes, and cardiovascular disease (CVD) associated with IFG.
RESEARCH DESIGN AND METHODS-Three studies were used: 1) the 1998 National Health Survey (NHS98), a randomly selected cross-sectional sample of 4,723 subjects; 2) the Singapore Impaired Glucose Tolerance (IGT) Follow-up Study, a cohort study comprising 295 IGT and 292 normal glucose tolerance subjects (frequency matched for age, sex, and ethnic group) followed up from 1992 to 2000; and 3) the Singapore CVD Cohort Study, comprising 5,920 subjects from three cross-sectional studies in whom the first ischemic heart disease (IHD) event was identified through linkage to registry databases. Risk of diabetes (Singapore IGT Follow-up study) was estimated using logistic regression adjusted for age, sex, and ethnicity. Risk of IHD (Singapore CVD cohort) was estimated using stratified (by study, from which data were derived) Cox's proportional hazards models adjusted for age, sex, and ethnicity.RESULTS -Lowering the criterion for diagnosing IFG to 5.6 mmol/l increased the prevalence of IFG from 9.5 to 32.3% in the NHS98. The lower cutoff identified more subjects at risk of diabetes and IHD, but the relative risk was lower than that for IGT.CONCLUSIONS -Greater efforts to identify those with IGT, or a group at similar risk of diabetes and CVD, may be a more efficient public health measure than lowering the FPG criterion for diagnosing IFG.
Diabetes Care 27:1728 -1734, 2004T he American Diabetes Association had previously recommended (1) the recognition of impaired fasting glucose (IFG) as a category of glucose tolerance analogous to impaired glucose tolerance (IGT). It was recommended that IFG be diagnosed in those with fasting plasma glucose (FPG) between 6.1 and 6.9 mmol/l. Since then, many analyses have examined the equivalence of FPG and 2-h postchallenge glucose (2-h PG) in predicting both diabetes and cardiovascular disease (CVD). Several key findings have emerged from these studies. First, the association between IGT and CVD events and mortality is stronger than that for IFG (2,3). Second, although IFG and IGT identify some of the same individuals, the degree of overlap is variable (4,5). As a consequence of the recommendations to use FPG rather than 2-h PG for the diagnosis of diabetes, many subjects with IGT, who are at risk of future CVD events, would not be identified.On the basis of the aforementioned findings, the American Diabetes Association has recently recommended (6) that the lower limit for the diagnosis of IFG be changed from 6.1 to 5.6 mmol/l. However, the need for this change has been questioned by others (7,8). Singapore is a small country in Asia with a high prevalence of diabetes and IGT. As in Europe and the U.S., we have found that IFG and IGT often identify different individuals. Only 26% of subjects with IGT had IFG (as defined by the older criteria of FPG 6.1-6.9 mmol/l),...