Adverse effects of obesity on β-cell function in Japanese subjects with normal glucose tolerance

Yuko Akehi, Keizo Anzai, Hitoshi Katsuta, Ryoko Yoshida, Kumiko Ohkubo, Takaaki Yamashita, Hironobu Kawashima, Junko Ono

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Abstract

The purpose of the present study was to elucidate the role of obesity in both early- and late-phase insulin secretion during an oral glucose tolerance test (OGTT) performed with 75 g glucose in Japanese subjects. This was performed using indices of β-cell function adjusted for insulin sensitivity. Of 155 subjects assessed, 68 had normal glucose tolerance (NGT) and 87 had impaired glucose tolerance (IGT). We used the homeostasis model assessment-insulin resistance (HOMA-IR) index as an indicator of insulin sensitivity. As indicators of β-cell function, we used the HOMA-β index, an insulinogenic index (ΔI30/ΔG30), and ΔAUC I/G(0-120), which were obtained in the OGTT. We then reevaluated the results after adjusting the β-cell function for insulin sensitivity ([ΔI30/ΔG30]/HOMA-IR index and [ΔAUC I/G(0-120)]/HOMA-IR index). β-Cell function was observed to reduce as the glucose tolerance deteriorated from NGT to IGT. However, when the effects of obesity were considered, the obese subjects with NGT already showed a decline in the (ΔAUC I/G(0-120))/HOMA-IR index value when compared with the nonobese subjects with NGT, despite the fact these subjects did not differ with regard to (ΔI30/ΔG30)/HOMA-IR index. As the glucose tolerance deteriorated to IGT, both (ΔI30/ΔG30)/HOMA-IR index and (ΔAUC I/G(0-120))/HOMA-IR index decreased to an identical extent in both subgroups. These data indicate that obesity causes a decrease in insulin secretion, especially during the late phase following a glucose load, even if the glucose tolerance remains normal.

Original languageEnglish
Pages (from-to)195-202
Number of pages8
JournalObesity Research and Clinical Practice
Volume2
Issue number3
DOIs
Publication statusPublished - Sep 1 2008
Externally publishedYes

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All Science Journal Classification (ASJC) codes

  • Endocrinology, Diabetes and Metabolism
  • Nutrition and Dietetics

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