Insulin resistance and insulin secretion at varying levels of glucose

ABSTRACT

To compare the insulin resistance and insulin secretion among the subjects with impaired fasting glucose, normal glucose tolerance, impaired glucose tolerance [IGT], and type 2 diabetes mellitus by Homeostasis model assessment [HOMA]. Comparative cross-sectional study. This study carried out from January 2006 to October 2006, at the department of pathology PNS Shifa Karachi. One hundred individuals [male 69 and female 31] were subjected to oral glucose tolerance test [OGTT]. These individuals were classified into four groups, based on the results of 75-g OGTT. 1] Normal glucose tolerance [NGT]. 2] Impaired fasting glucose [IFG]. 3] Impaired glucose tolerance [IGT]. 4] Diabetes mellitus [DM]. We used the HOMA for the calculation of insulin resistance [IR] and insulin secretion [HOMA-beta cell]. The mean HOMA-IR was highest in IFG and DM. No significant difference in HOMA-IR was noted between IFG vs. IGT and DM [4.18 +/- 2.32, p>0.05]. The IGT group had significantly low HOMA-IR as compared to DM. IGT subjects had significantly high mean HOMA-beta cell function [171.1 +/- 117 p<0.003] from DM group. NGT group subjects had no significant difference in HOMA-beta cell function as compared to IFG and IGT [145.58 +/- 130.0, p>0.005]. IFG group subjects had no significant difference in HOMA-beta cell function as compared to IGT and DM [119.8 +/- 53.9 p>0.05]. The insulin resistance and insulin secretion are different at the different levels of glucose tolerance. IFG group has high insulin resistance and low insulin secretion, which is comparable to DM, while IGT group has low insulin resistance and high insulin secretion as compared to DM