[Comparison between diabetes incidence using different cut points of IFG: Tehran lipid glucose study [TLGS]]

ABSTRACT

In 2003, the American diabetes Association [ADA] recommended that the definition for a cut off of impaired fasting glucose [IFG] should be changed to 100-125 mg/dl. This study has examined the effect of different cut points for IFG on diabetes incidence in Tehran's urban population. A total of 4929 [non-diabetic adults], aged 20-86 years, participants of the Tehran Lipid Glucose Study, were followed for diabetes incidence [based on FBS and glucose tolerance tests] for 3.5 years and were divided into various groups, normoglycemia < 100, original IFG 110-125, added IFG 100-110 and new IFG 100-125 mg/dL. Odds ratio for diabetic incidence after adjustment for confounding factors with logistic regression model was measured. The mean ages were 42.9 +/- 13.7 [minimum 20 and maximum 86 years old]; 59.1% of participants were female [n= 2916]. Prevalences of original IFG, added IFG and new IFG were 3.7% [n=183], 11.8% [n= 584], 15.5% [n= 767] respectively. At the end of study, 188 cases [3.8%] were diabetic. Incidence of diabetes in the normoglycemia, original IFG, added IFG and new IFG groups were 1.8% [n= 76], 26.2% [n= 48], 11% [n= 64], and 14.6% [n= 112] respectively. Odds ratios for diabetes incidence after adjustment for age/sex and confounding factors compared with normglycemia, diabetes incidence were 11.4 [7.4-17.6], 4.7 [3.3-6.8], 6.3 [4.5-8.5] for original IFG, added IFG, and new IFG respectively. The new IFG definition does not appear to have enhanced ability to predict diabetes incidence compared to the original IFG definition