The Relation of Fasting and 2-h Postchallenge Plasma Glucose Concentrations to Mortality

Abstract

OBJECTIVE -Under the auspices of the National Institutes of Health, American Diabetes Association, and World Health Organization, expert committees lowered the fasting plasma glucose (FPG) concentration diagnostic for diabetes from 7.8 to 7.0 mmol/l and defined 6.1-6.9 mmol/l as impaired fasting glucose (IFG) and Ͻ6.1 mmol/l as normal fasting glucose. In 2003, IFG was lowered to 5.6 -6.9 mmol/l and normal fasting glucose to Ͻ5.6 mmol/l. Reports of the relationship between glucose concentration and all-cause mortality have been inconsistent. It is not known if the 2-h plasma glucose (2hPG) concentration from an oral glucose tolerance test (OGTT) adds to the predictive power of FPG.RESEARCH DESIGN AND METHODS -We followed 1,236 men for an average of 13.4 years to determine the relationship between both FPG and 2hPG and all-cause mortality.RESULTS -Risk for mortality did not increase until the FPG exceeded 6.1 mmol/l. Risk increased by ϳ40% in the 6.1-6.9 mmol/l range and doubled when FPG ranged from 7.0 to 7.7 mmol/l. A combination of the 2hPG and FPG allowed better estimation of risk than the FPG alone. Within any category of FPG, risk generally increased as the 2hPG increased, and within any category of 2hPG, risk generally increased as the FPG increased.CONCLUSIONS -These data support the decision to lower the FPG diagnostic for diabetes from 7.8 to 7.0 mmol/l, show that both IFG and impaired glucose tolerance have risks between the normal and diabetic ranges, and show that the OGTT adds predictive power to that of FPG alone and should not be abandoned. The lowering of IFG to 5.6 mmol/l from 6.1 mmol/l, at least for mortality, is, however, not supported by our results. (5), and 1999 (6). Over this 25-year period, standards for interpreting the oral glucose tolerance test (OGTT) were identical and unchanged in the U.S. and WHO reports; an impaired zone was defined as 140 -199 mg/dl (7.8 -11.0 mmol/l) and the diabetic cut point was defined as 200 mg/dl (11.1 mmol/l). The standards for interpreting the FPG changed over the years. In the early reports, no impaired zone was defined (1,4,5). Both the U.S. and WHO committees recommended that the cut point for diabetes be 140 mg/dl (7.8 mmol/l). In subsequent reports, the U.S. (2) and WHO (6) recommended that an impaired fasting glucose (IFG) zone of 110 -125 mg/dl (6.1-6.9 mmol/l) be created and also that the diabetic cut point be lowered to 126 mg/dl (7.0 mmol/l). Most recently (3), the U.S. committee changed the IFG zone to 100 -125 mg/dl (5.6 -6.9 mmol/l). Inevitably, data from population studies have become difficult to compare and to interpret because the definitions of impaired and diabetic test results have changed. Diabetes CareThe purpose of the present study is to examine the risks of mortality from these variously defined categories of glucose metabolism, to evaluate whether the OGTT adds power to the FPG value as a predictor of risk, and to examine the literature critically with respect to these questions.RESEARCH DESIGN AND METHODS -The 1,236 men include...

The threshold for diagnosing impaired fasting glucose: a position statement by the European Diabetes Epidemiology Group

“…However, when IFG was defined as 5.6-6.9 mmol/l, the predictive value of IFG was abolished and the mortality risks were diminished substantially because of the inclusion of the 5.6-6.1 mmol/l group, in which the RR ranged nonsignificantly between 0.9 and 2.5 [10]. The findings were replicated for total mortality in the Baltimore Longitudinal Study of Aging [13]. Among 1,236 men followed for 13 years, the risk of mortality did not increase until the FPG exceeded 6.1 mmol/l.…”

“…Among 1,236 men followed for 13 years, the risk of mortality did not increase until the FPG exceeded 6.1 mmol/l. The RR for mortality was 1.03 (95% CI 0.80-1.32) in the FPG group 5.6-6.1 mmol/l, whereas the risk was elevated by 40% in the FPG group 6.1-6.9 mmol/l (RR 1.41, 1.01-1.97), the authors finding no support for the lowering of IFG to 5.6 mmol/l from 6.1 mmol/l for the outcome of mortality [13]. Nearly identical findings were reported from the Dutch Hoorn study, in which the age-and sex-adjusted RR for CVD mortality was 1.43 (0.79-2.60) in the FPG group 6.1-6.9 mmol/l, but 0.63 (0.34-1.19) in the new IFG group of 5.6-6.0 mmol/l [14].…”

All Pre-Diabetes Is Not the Same: Metabolic and Vascular Risks of Impaired Fasting Glucose at 100 Versus 110 mg/dl

“…The Baltimore Longitudinal Study of Aging has shown that mortality is increased in men by levels of FPG Ͼ110 mg/dl and/or 2-h OGTT glucose levels Ͼ140 mg/dl, even after adjustment for the presence of other risk factors (12), and mortality was also independently increased by the presence of postchallenge hyperglycemia in men in the Whitehall Study (13) and in both men and women in the DECODE (Diabetes Epidemiology: Collaborative Analysis of Diagnostic Criteria in Europe) study (14). Although it is not yet established in randomized controlled trials that mortality and/or cardiovascular events can be decreased in individuals with such mild hyperglycemia by interventions other than treatment with acarbose (15), the hypothesis is being tested in ongoing studies with rosiglitazone, nateglinide, ramipril, and valsartan.…”

Random Plasma Glucose in Serendipitous Screening for Glucose Intolerance: Screening for Impaired Glucose Tolerance Study 2

“…We focused particularly on diabetes and abnormal glucose tolerance 110 (AGT 110 , diabetes or IGT or IFG 110 ), as such levels confer increased mortality. 23,24 Receiver operating characteristic (ROC) curve analysis was used to evaluate the discriminative effectiveness of random plasma glucose. The area under the ROC curve (AROC) is the index of effectiveness, with 1.0 indicating perfect discrimination and 0.5 chance discrimination.…”