Factors responsible for development from normal glucose tolerance to isolated postchallenge hyperglycemia.
OBJECTIVE
Isolated postchallenge hyperglycemia (IPH), defined as fasting plasma glucose (FPG) level <7.0 mmol/l and 2-h plasma glucose (PG) level >/=11.1 mmol/l, is a subtype of early-stage diabetes. This study evaluates the metabolic profiles of insulin secretion and insulin sensitivity in IPH to clarify the factors responsible for development of this form of type 2 diabetes.


METHODS
We conducted cross-sectional analysis of 231 Japanese men aged 20-70 years. The subjects were classified into the following three groups, based on the results of a 75-g oral glucose tolerance test (OGTT): 1) normal glucose tolerance (NGT), defined as FPG level <6.1 mmol/l and 2-h PG level <7.8 mmol/l (n = 89); 2) impaired glucose tolerance (IGT), defined as FPG level <7.0 mmol/l and 2-h PG level of 7.8-11.1 mmol/l (n = 94); and 3) IPH (n = 48). We compared the three groups for insulin secretion (insulinogenic index) and insulin sensitivity (index of insulin resistance using homeostasis model assessment [HOMA-IR]).


RESULTS
The insulinogenic index in IPH was the lowest of the three groups (P < 0.001 versus NGT). The HOMA-IR in the IGT and IPH groups were significantly higher than in the NGT group (P < 0.001), but both were similar. By linear regression analysis, the insulinogenic index rather than fasting insulin or HOMA-IR was the more significant factor in the 2-h PG level in IGT and IPH.


CONCLUSIONS
Subjects with IPH exhibited distinctly impaired early-phase insulin secretion and only mild insulin resistance, indicating that reduced insulin secretion is the primary determinant of deterioration from NGT to IGT and IPH in development of type 2 diabetes in these subjects.
Suzuki
Haruhiko
H
Department of Diabetes and Clinical Nutrition, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
Fukushima
Mitsuo
M
Usami
Masaru
M
Ikeda
Masaki
M
Taniguchi
Ataru
A
Nakai
Yosikatsu
Y
Matsuura
Toshifumi
T
Kuroe
Akira
A
Yasuda
Koichiro
K
Kurose
Takeshi
T
Seino
Yutaka
Y
Yamada
Yuichiro
Y
D000328:Adult; D000368:Aged; D044466:Asian People; D001786:Blood Glucose / Q000378:metabolism*; D003430:Cross-Sectional Studies; D003920:Diabetes Mellitus / Q000235:genetics; D005190:Family; D005215:Fasting; D005951:Glucose Tolerance Test / Q000379:methods*; D006442:Glycated Hemoglobin / Q000032:analysis; D006029:Glycosuria; D006801:Humans; D006943:Hyperglycemia / Q000097:blood*; D007328:Insulin / Q000097:blood; D007564:Japan; D008297:Male; D008875:Middle Aged; D019518:Postprandial Period; D012016:Reference Values; D012044:Regression Analysis
D001786:Blood Glucose; D006442:Glycated Hemoglobin; D007328:Insulin