Fasting tests of insulin secretion and sensitivity predict future prediabetes in Japanese with normal glucose tolerance.
Aims/Introduction:  Reduced insulin sensitivity and secretion are important in the pathogenesis of type 2 diabetes. Their relationships to prediabetes, impaired glucose tolerance (IGT) and impaired fasting glucose (IFG) have been previously studied with the oral glucose tolerance test (OGTT). We investigated whether or not baseline measures of insulin secretion and sensitivity obtained from fasting blood specimens were related to the development of prediabetes and how these measures compared with those based on the OGTT.


METHODS
In 152 Japanese subjects with normal glucose tolerance, we measured baseline plasma glucose and insulin after an overnight fast and during a 75 g OGTT, insulin resistance index (homeostasis model assessment [HOMA-IR]), and insulin secretion (insulinogenic index [30 min insulin - fasting insulin] ÷ [30 min glucose - fasting glucose] or HOMA-β).


RESULTS
At a 5-6 year (mean 5.7 years) follow-up examination, we confirmed 36 cases of prediabetes. After adjusting for age, sex, family history of diabetes, body mass index, and 2-h plasma glucose, the odds ratio comparing the lowest tertile (≤0.82) of insulinogenic index with the highest tertile (≥1.43) was 6.98 (95% confidence interval, 1.96-24.85) and was 10.72 (2.08-55.3) comparing the lowest tertile (≤76.3) of HOMA-β with the highest tertile (≥122.1), whereas the respective odds ratios of HOMA-IR were 3.74 (1.03-13.57) and 10.89 (1.93-61.41) comparing the highest tertile (≥1.95) with the lowest tertile (≤1.25).


CONCLUSIONS
Lower insulin secretion and sensitivity are independent risk factors for prediabetes. Clinically practical identification of those at risk for prediabetes is obtainable from HOMA-β and HOMA-IR, both of which are measured in fasting state. (J Diabetes Invest, doi: 10.1111.j.2040-1124.2010.00041.x, 2010).
Department of Diabetes and Metabolism, the Institute for Adult Diseases, Asahi Life Foundation.
Yukiko
Y
Onishi
Department of Preventive Medicine and Environmental Health, Osaka City University Graduate School of Medicine, Osaka ; Epidemiologic Research Information Center and Department of Medicine, Veterans Affairs Puget Sound Health Care System.
Tomoshige
T
Hayashi
Department of Preventive Medicine and Environmental Health, Osaka City University Graduate School of Medicine, Osaka.
Kyoko Kogawa
KK
Sato
Division of Internal Medicine, Hitachi General Hospital, Ibaraki.
Takehide
T
Ogihara
Department of Endocrinology and Metabolism, Yokohama Sakae Kyosai Hospital, Yokohama, Japan.
Nobuaki
N
Kuzuya
Laboratory for Systems Biology and Medicine, Research Center for Advanced Science and Technology, University of Tokyo, Tokyo.
Motonobu
M
Anai
Department of Diabetes and Metabolism, the Institute for Adult Diseases, Asahi Life Foundation.
Katsunori
K
Tsukuda
Epidemiologic Research Information Center and Department of Medicine, Veterans Affairs Puget Sound Health Care System ; Department of Medicine, University of Washington, Seattle, Washington, USA.
Edward J
EJ
Boyko
Department of Medicine, University of Washington, Seattle, Washington, USA.
Wilfred Y
WY
Fujimoto
Department of Diabetes and Metabolism, the Institute for Adult Diseases, Asahi Life Foundation.
Masatoshi
M
Kikuchi
Epidemiology; Glucose intolerance; Insulin resistance