title: Impact of serum triglyceride and high density lipoprotein cholesterol levels on early-phase insulin secretion in normoglycemic and prediabetic subjects.
abstract: BACKGROUND
  Increased triglycerides (TGs) and decreased high density lipoprotein cholesterol (HDL-C) levels are established as diabetic risks for nondiabetic subjects. The aim of this study was to investigate the relationship among TG, HDL-C, TG/HDL-C ratio, and early-phase insulin secretion in normoglycemic and prediabetic subjects.
  
  
  METHODS
  We evaluated 663 Japanese subjects who underwent the 75-g oral glucose tolerance test. On the basis of these results, the subjects were divided into four groups: those with normal glucose tolerance (NGT; n=341), isolated impaired fasting glucose (i-IFG; n=211), isolated impaired glucose tolerance (i-IGT; n=71), and combined IFG and IGT (IFG+IGT; n=40). Insulin secretion was estimated by the insulinogenic index (IGI) (Δinsulin/Δglucose [30 to 0 minutes]) and disposition index (DI) (IGI/homeostasis model assessment of insulin resistance).
  
  
  RESULTS
  In prediabetic subjects (i-IFG, i-IGT, and IFG+IGT), linear regression analyses revealed that IGI and DI were positively correlated with HDL-C levels. Moreover, in subjects with i-IGT and (IFG+IGT), but not with i-IFG, the indices of insulin secretion were negatively correlated with the log-transformed TG and TG/HDL-C ratio. In both the subjects with i-IGT, multivariate linear regression analyses revealed that DI was positively correlated with HDL-C and negatively with log-transformed TG and TG/HDL-C ratio. On the other hand, in subjects with NGT, there was no association between insulin secretion and lipid profiles.
  
  
  CONCLUSIONS
  These results revealed that serum TG and HDL-C levels have different impacts on early-phase insulin secretion on the basis of their glucose tolerance status.
authors.affiliation: Department of Internal Medicine, Iida Municipal Hospital, Iida, Japan. ; Division of Laboratory Medicine, Department of Pathology and Microbiology, Nihon University School of Medicine, Tokyo, Japan.
authors.forename: Masanori
authors.initials: M
authors.lastname: Shimodaira
authors.affiliation: Department of Internal Medicine, Iida Municipal Hospital, Iida, Japan.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Niwa
authors.affiliation: Department of Internal Medicine, Iida Municipal Hospital, Iida, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Nakajima
authors.affiliation: Department of Internal Medicine, Iida Municipal Hospital, Iida, Japan.
authors.forename: Mutsuhiro
authors.initials: M
authors.lastname: Kobayashi
authors.affiliation: Department of Internal Medicine, Iida Municipal Hospital, Iida, Japan.
authors.forename: Norinao
authors.initials: N
authors.lastname: Hanyu
authors.affiliation: Division of Laboratory Medicine, Department of Pathology and Microbiology, Nihon University School of Medicine, Tokyo, Japan.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Nakayama
keywords: Cholesterol, HDL; Diabetes; Insulin secretion; Triglycerides