Insulin resistance assessed by short insulin tolerance test and its association with obesity and insulin resistance-related parameters in humans: A pilot randomized trial

Abstract

The aim of this study was to examine the association of insulin resistance (evaluated by the short insulin tolerance test [SITT]) with parameters related to obesity and insulin resistance. We prospectively recruited controls and patients with type 2 diabetes mellitus (T2DM), subjected them to the SITT, and calculated the K indices of the intravenous insulin tolerance test (KITT(iv)) and the subcutaneous insulin tolerance test (KITT(sc)). We compared KITT(iv) results between the volunteers and patients and examined its correlation with KITT(sc). We also examined the association of KITT(iv) with obesity, insulin resistance-related parameters, and the insulin dose required for glycemic control. A total of 24 participants (seven controls and 17 patients with T2DM) were studied. The mean KITT(iv) was significantly lower in patients with T2DM than in the controls (2.5%±2.1% vs. 4.5%±1.8%). In all participants, KITT( iv) was significantly correlated with the homeostasis model assessment for insulin resistance (HOMA-IR) values (r = -0.601, p<0.05) but not with KITT(sc) (p = 0.62). KITT(iv) was correlated positively with the serum adiponectin concentration, but negatively with the visceral fat area and serum concentrations of tumor necrosis factor-α and branched-chain amino acids. In patients with T2DM, KITT(iv) and HOMA-IR values were significantly correlated with the total insulin dose required for glycemic control. Insulin resistance evaluated using KITT(iv) was correlated with the HOMA-IR values, but not with the resistance evaluated using KITT(sc). The degree of insulin resistance was associated with biomarkers, such as adiponectin, tumor necrosis factor-α, branched-chain amino acids, the visceral fat area, and the dose of insulin required for glycemic control.