Ethnic differences in insulin sensitivity,β-cell function, and hepatic extraction between Japanese and caucasians: A minimal model analysis

Abstract

Context: Ethnic differences have previously been reported for type 2 diabetes. Design: This was a cross-sectional study with oral glucose tolerance tests to assessβ-cell function, hepatic insulin extraction, and insulin sensitivity. Participants: Participants included 120 Japanese and 150 Caucasian subjects. Objective: Weaimedat assessingthepotential differencesbetweenCaucasianandJapanesesubjects ranging from normal glucose tolerance (NGT) to impaired glucose tolerance (IGT) and to type 2 diabetes. Main Outcomes: Measures ofβ-cell function, hepatic extraction, and insulin sensitivity were assessed using C-peptide, glucose, and insulin minimal models. Results: Basalβ-cell function (φb) was lower in Japanese compared with Caucasians (P< .01). In subjects with IGT, estimates of the dynamic (φd) and static (φs)β-cell responsiveness were significantly lower in the Japanese compared with Caucasians (P< .05). In contrast, values of insulin action showed higher sensitivity in the Japanese IGT subjects. Hepatic extraction was similar in NGT and IGT groups but higher in Japanese type 2 diabetic subjects (P< .01). Despite differences in insulin sensitivity,β-cell function, and hepatic extraction, the disposition indices were similar between the 2 ethnic groups at all glucose tolerance states. Furthermore, the overall insulin sensitivity andβ-cell responsiveness for all glucose tolerance states were similar in Japanese and Caucasians after accounting for differences in body mass index. Conclusion: Our study provides evidence for a similar ability of Japanese and Caucasians to compensate for increased insulin resistance.