Nonalcoholic fatty liver is a risk factor for postprandial hyperglycemia, but not for impaired fasting glucose

Abstract

The first aim of this study was to elucidate the relationship between impaired glucose tolerance (IGT) and nonalcoholic fatty liver. The second was to make a rule regarding to whom 75-g oral glucose tolerance tests (OGTTs) should be applied to identify subjects with IGT and diabetes mellitus (DM) in the annual check-up at the human dry dock. A total of 716 subjects who visited the Department of General Medicine of the International Medical Center of Japan from May 2001 through January 2008 for an annual check-up at the human dry dock were analyzed. We evaluated risk factors related to nonalcoholic fatty liver using multivariate logistic regression analysis and compared the difference of body mass index (BMI) and glucose level at 75-g OGTT at two different time points in subjects whose fatty change had improved or worsened. Nonalcoholic fatty liver was strongly related to 2-h- and 1-h-post-challenge glucose level (P < 0.0001 and P = 0.018, respectively), but not fasting plasma glucose (FPG) (P = 0.706). The risk factors for IGT were nonalcoholic fatty liver (P < 0.05), low levels of high-density lipoprotein cholesterol (HDL-C) (P = 0.026) and age (P = 0.013). A clearly positive relationship was observed between the difference of BMI and 2-h-post-challenge glucose level among the subjects whose fatty change had improved or worsened (R = 0.6, P = 0.018). Nonalcoholic fatty liver was clearly related to the 2-h- or 1-h-post-challenge glucose level, but not to FPG, in 75-g OGTT, and this IGT was corrected by body weight reduction in accordance with diminished nonalcoholic fatty liver. Thus, 75-g OGTT should be applied to subjects with nonalcoholic fatty liver to evaluate IGT.