An Oral Disposition Index Predicts the Development of Future Diabetes Above and Beyond Fasting and 2-Hour Glucose Levels

  1. Kristina M. Utzschneider, MD (kutzschn{at}u.washington.edu)1,2,
  2. Ronald L. Prigeon, MD3,4,
  3. Mirjam V. Faulenbach, MD1,2,
  4. Jenny Tong, MD, MPH1,2,
  5. Darcy B. Carr, MD, MS5,
  6. Edward J. Boyko, MD, MPH6,
  7. Donna L. Leonetti, PhD7,
  8. Marguerite J McNeely, MD2,
  9. Wilfred Y. Fujimoto, MD2 and
  10. Steven E. Kahn, MB, ChB1,2
  1. 1Division of Metabolism, Endocrinology and Nutrition, Department of Medicine, Veterans Affairs Puget Sound Health Care System, Seattle, WA
  2. 2Department of Medicine, University of Washington, Seattle, WA
  3. 3Geriatric Research Education and Clinical Center (GRECC), Baltimore Veterans Affairs Medical Center, Baltimore, MD, USA
  4. 4Division of Gerontology, University of Maryland School of Medicine, Baltimore, MD
  5. 5Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, University of Washington, Seattle, WA
  6. 6Epidemiologic Research and Information Center, Veterans Affairs Puget Sound Health Care System, Seattle, WA
  7. 7Department of Anthropology, University of Washington, Seattle, WA

    Abstract

    Objective: We sought to determine if an oral disposition index (DIO) predicts the development of diabetes over a 10 year period. First, we assessed the validity of DIO by demonstrating that a hyperbolic relationship exists between oral indices of insulin sensitivity and β-cell function.

    Research design and methods: 613 Japanese American subjects (322M/291F) underwent a 75-gram oral glucose tolerance test (OGTT) at baseline, 5 and 10 years. Insulin sensitivity was estimated as 1/fasting insulin or HOMA-S. Insulin response was estimated as the change in insulin divided by change in glucose from 0-30 minutes (ΔI0-30/ΔG0-30).

    Results: ΔI0-30/ΔG0-30 demonstrated a curvilinear relationship with 1/fasting insulin and HOMA-S with a left and downward shift as glucose tolerance deteriorated. The confidence limits for the slope of the loge-transformed estimates included -1 for ΔI0-30/ΔG0-30 vs. 1/fasting insulin for all glucose tolerance groups, consistent with a hyperbolic relationship. When HOMA-S was used as the insulin sensitivity measure, the confidence limits for the slope included -1 only for subjects with NGT or IFG/IGT, but not diabetes. Based on this hyperbolic relationship, the product of ΔI0-30/ΔG0-30 and 1/fasting insulin was calculated (oral disposition index: DIO) and decreased from NGT to IFG/IGT to diabetes (p<0.001). Among non-diabetic subjects at baseline, baseline DIO predicted cumulative diabetes at 10-years (p<0.001) independent of age, sex, BMI, family history of diabetes and baseline fasting and 2-hour glucose.

    Conclusions: DIO provides a measure of β-cell function adjusted for insulin sensitivity and is predictive of development of diabetes over 10 years.

    Footnotes

      • Received August 11, 2008.
      • Accepted October 16, 2008.

    This Article

    1. Published online before print October 28, 2008, doi: 10.2337/dc08-1478
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