One-hour plasma glucose as a predictor of the development of Type 2 diabetes in Japanese adults

Aims To test the hypothesis that 1‐h plasma glucose in an oral glucose tolerance test is a better predictor of the development of diabetes than 2‐h plasma glucose, independently of indices of insulin secretion or action in Japanese adults. Methods A historical cohort study was conducted in 1445 Japanese workers who did not have diabetes. The association between 1‐h plasma glucose and the development of Type 2 diabetes was analysed. Results Overall, 95 of the study participants developed Type 2 diabetes during a mean follow‐up of 4.5 years. The area under the receiver‐operating characteristic curve for 1‐h plasma glucose for future diabetes [0.88 (95% CI 0.84–0.91)] was greater than that for 2‐h plasma glucose [0.79 (95% CI 0.74–0.84)], and for insulinogenic [0.73 (95% CI 0.68–0.78)] and disposition indices [0.79 (95% CI 0.74–0.84); P < 0.05]. Compared with the first quartile, the hazard ratio for future diabetes in the fourth quartile of 1‐h plasma glucose was 42.5 [95% CI 5.7–315.2 (P < 0.05)] and the hazard ratio in the fourth quartile of 2‐h plasma glucose was 4.4 [95% CI 1.8–10.8 (P < 0.05)], after adjustments for covariates including fasting plasma glucose. The significance of the elevated hazard ratio in the fourth quartile of 1‐h plasma glucose was maintained after adjustments for 2‐h plasma glucose, insulinogenic index or disposition index, whereas the elevation of the hazard ratio in the fourth quartile of 2‐h plasma glucose was diminished and was no longer significant after adjustments for 1‐h plasma glucose. Conclusions One‐hour plasma glucose had a greater association with the future development of Type 2 diabetes than did 2‐h plasma glucose, independently of oral glucose tolerance test‐derived indices of insulin action in a Japanese population. What's new? The study confirmed the superior predictive ability of 1‐h plasma glucose to that of 2‐h plasma glucose with regard to the development of diabetes and that this finding can be generalized to an Asian population. The association between 1‐h plasma glucose and the future development of diabetes was independent of indices of insulin secretion or action as assessed by insulinogenic index or disposition index. The results of receiver‐operating characteristic curve analysis showed that the predictive ability of indices of insulin secretion or action were not superior to that of sampling plasma glucose at 1 h.