Clinical characteristics of Japanese Americans with normal glucose tolerance with 1-h hyperglycemia: A cross-sectional study.

Aims/introduction: High 1-h plasma glucose levels have an increased risk of type 2 diabetes. To determine the pathophysiological features in participants with normal glucose tolerance (NGT) with 1-h hyperglycemia (HG), we investigated the variability in the glucagon and insulin secretions after oral glucose loading and nutrient survey.

Materials and methods: A 75-g oral glucose tolerance test (OGTT) was performed in Japanese Americans (aged 40-75 years), enrolled in medical surveys conducted in 2015. We recruited only participants with NGT defined as fasting glucose values <110 mg/dL and 2-h glucose levels <140 mg/dL. We evaluated homeostatic model assessment for insulin resistance (HOMA-IR), insulin sensitivity index (MATSUDA-Index), insulin, and glucagon (GCG) secretions during the 75-g OGTT and compared them between 1-h serum glucose values: <155 mg/dL (1-h non-hyperglycemia: NHG, n = 76) and 1-h serum glucose values: ≥155 mg/dL (HG, n = 41). We also conducted a dietary intake survey to determine the association between 1-h serum glucose and nutritional intake in the usual diet.

Results: The HG group demonstrated significant insulin resistance compared to the NHG group. Two-h GCG levels were significantly lower in the HG group. Additionally, low vegetable fat intake was significantly associated with 1-h HG after adjusting for sex, age, and body mass index.

Conclusions: Insulin resistance is already present in the HG group. Vegetable fat intake may be associated with glucose metabolism regardless of clinical background.