Insulin secretion and insulin resistance in newly diagnosed, drug naive prediabetes and type 2 diabetes patients with/without metabolic syndrome

The relationships between insulin secretion and resistance in subjects with newly diagnosed prediabetes (preDM) and type 2 DM according to the presence of metabolic syndrome (MS) were controversial. We performed OGTT on 322 drug naive subjects with a history of hyperglycemia of ≤3 months, and divided into three groups, NGT, preDM (IFG and/or IGT), and T2DM. We also diagnosed these subjects with respect to MS according to ATP III criteria modified by Asia-Pacific guidelines and compared IGI and HOMA-IR. When compare groups stratified by the presence of MS, preDM and T2DM groups with MS showed significantly higher mean HOMA-IR and IGI than those without. When compare groups with respect to glucose tolerance, NGT, preDM, and T2DM subgroups in MS group showed significant higher HOMA-IR and lower IGI according to glucose tolerance. However, NGT, preDM, and T2DM subgroups in non-MS group showed a significant decrease in IGI but no significant difference in HOMA-IR as glucose tolerance worsened. In conclusion, deterioration in IGI and aggravation of HOMA-IR are both important in the primary pathogenesis of diabetes in those with MS. However, IGI deterioration may be the only important factor in the primary pathogenesis of T2DM in the absence of MS.