Normalization of impaired glucose tolerance after kidney transplantation is associated with improved ß-cell function.

Our previous study revealed that over 50% of recipients with pretransplant impaired glucose tolerance (IGT) improved to normal glucose tolerance after kidney transplantation. However, the mechanism is unclear. We aimed to investigate whether the changes in glucose tolerance are associated with ß-cell function and insulin resistance in Japanese kidney transplant recipients with pretransplant IGT. Of the 265 recipients who received kidney transplantation, 54 with pretransplant IGT were included. We divided the recipients into improvement and nonimprovement groups according to the change in the area under the curve for glucose obtained from the oral glucose tolerance test (OGTT). ß-Cell function was estimated by the insulin secretion sensitivity index-2 (ISSI-2) and the disposition index (DI). Insulin resistance was estimated by the Matsuda index (MI) and the homeostasis model assessment of insulin resistance (HOMA-IR). ISSI-2 and DI increased significantly after transplantation in the improved group (P < 0.01, P < 0.05, respectively), but not in the nonimproved group. ΔISSI-2 and ΔDI were significantly and positively associated with pretransplant 60-min OGTT plasma glucose levels (both P < 0.01). There were no differences in MI or HOMA-IR between these two groups after transplantation. In recipients not on pretransplant dialysis, a significant negative association was found between Δblood urea nitrogen (BUN) and ΔDI (correlation coefficient = -0.48, P < 0.05). In pretransplant IGT recipients, improvements in glucose tolerance after kidney transplantation were linked to improvements in ß-cell function. The higher the 60-min OGTT plasma glucose level, the greater the improvement in posttransplant ß-cell function. Improvements in BUN after transplantation were associated with improvements in ß-cell function.NEW & NOTEWORTHY In recipients with pretransplant impaired glucose tolerance, improvements in glucose tolerance after kidney transplantation were associated with improvements in ß-cell function. The higher the pretransplant 60-min OGTT plasma glucose level, the greater the improvement in posttransplant ß-cell function. Although glucose tolerance is known to be impaired after transplantation, the present study focused on the reason for the improvement in glucose tolerance rather than the development of posttransplantation diabetes mellitus.

Alanine aminotransferase and γ-glutamyltransferase as markers for elevated insulin resistance-associated metabolic abnormalities in obese Japanese men younger than 30 years of age.

OBJECTIVE: This study aimed to understand whether liver function tests predict insulin resistance and its associated metabolic abnormalities in obese young men who are younger than 30 years of age. METHODS: In this cross-sectional study, we determined anthropometric and metabolic parameters and the homeostasis model assessment of insulin resistance (Homa-IR) in 208 obese young Japanese men (age, 18-29 years; BMI ± SD, 31.3 ± 3.1 kg/m(2)). RESULTS: After adjusting for age and BMI, alanine aminotransferase (ALT) and γ-glutamyltransferase (GGT) were significantly associated with Homa-IR. Both ALT and GGT but not fasting glucose levels had significant positive associations with total cholesterol, LDL, TG, and UA. After adjusting for ALT, GGT remained a significant predictor of total cholesterol, LDL, TG, and UA, but ALT did not remain a significant predictor of these variables after adjusting for GGT. CONCLUSION: ALT and GGT have significant associations with insulin resistance and its associated metabolic abnormalities in obese young Japanese men. ALT and GGT may be used as markers of insulin resistance-associated metabolic abnormalities in this cohort.

Waist circumference is positively associated with insulin resistance but not with fasting blood glucose among moderately to highly obese young Japanese men.

OBJECTIVE: To investigate the association of waist circumference with insulin resistance in obese young Japanese men. METHODS: In this cross-sectional study, we evaluated 92 obese young Japanese men (age: 18-29 years; mean BMI ± SD: 33 ± 3 kg/m(2)) for anthropometric and metabolic parameters and the homeostasis model assessment of insulin resistance (Homa-IR). RESULTS: Waist circumference ranged from 87.5 cm to 129 cm. Subjects with waist circumferences in the top quartile had higher insulin (Ln-transformed) and Homa-IR (Ln-transformed) compared with those in the bottom quartile. Fasting blood glucose and HbA1c were lower among subjects in the second-lowest quartile but not the second-highest quartile or the top quartile compared with those in the bottom quartile. CONCLUSION: Insulin resistance is associated with waist circumference in moderately to highly obese young Japanese men. Suppression of blood glucose by enhanced insulin secretion triggered by the increase of insulin resistance may begin to lose its effect as waist circumference becomes larger.