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Using The One-Hour Postload Glucose Can Predict Future Diabetes

12-year community-based cohort study investigated whether 1-h glucose concentration could be better indicator of diagnosis.

The objective of a 12-year community-based cohort study was to determine if the plasma glucose concentration at 1 hr during an oral glucose tolerance test (OGTT) may be a better predictor of future diabetes mellitus than the fasting or 2-h postload glucose concentration for the Asian population. A total of 5,703 Koreans with normal glucose tolerance were enrolled. Indices of insulin sensitivity and β-cell function estimated from standard 75-g OGTTs performed every 2 years for 12 years were used to identify whether the 1-h glucose concentration could predict future diabetes mellitus.

The mean age and body mass index at baseline were 51·3 ± 8·7 years and 24·2 ± 3·0 kg/m2, respectively. During the 12-year follow-up, 593 subjects (10·3%) developed diabetes mellitus. After adjusting for typical risk factors, subjects with a 1-h postload glucose concentration ≥8·0 mmol/l had lower β-cell function and a 2·84-fold increased risk of incident diabetes mellitus compared with their counterparts.

Conclusions In this community-based 12-year prospective cohort study, 1-h postload plasma glucose concentration was an independent predictor of future diabetes mellitus and 144mg/dL. (8·0 mmol/l) was suggested as a cut-off value.

In Caucasian studies, 1-h postload glucose concentration has been found to have additional predictive power of the future development of diabetes mellitus when added to the FPG. A cut-off value of 155 mg/dl (8·5 mmol/l) was adopted to identify high-risk subjects from the data of the San Antonio Heart Study and the Botnia Study. The NGT subjects with high 1-h postload glucose concentration ≥153mg/dL.(≥8·5 mmol/l) had worse insulin sensitivity and β-cell function compared with those with low 1-h postload glucose concentration <153mg/dL.(<8.5mmol/l). These findings were consistently observed in a Hispanic ethnic group. Therefore, the1-h postload plasma glucose concentration is likely to be a good marker for stratification of future risk of diabetes mellitus in people with NGT.

During 12-year follow-up, 593 subjects (10·3%) developed diabetes mellitus. The mean time of progression to diabetes mellitus was 6·8 ± 3·3 years. Those who progressed to diabetes mellitus (‘progress’ group) were older and had greater mean BMI than those who did not (‘nonprogress’ group), and more men than women progressed to diabetes mellitus. Waist circumference, waist-to-hip ratio, systolic and diastolic blood pressure, plasma concentrations of glucose, total cholesterol, LDL cholesterol, triglyceride, AST, ALT, creatinine, hsCRP and HbA1c level were higher in the progress group than in the nonprogress group.

From the results In this population-based longitudinal study, Koreans with normal glucose tolerance whose 1-h postload plasma glucose concentration was 144mg/dL.(≥8·0 mmol/l) had 2·51-fold increase in the incidence of diabetes mellitus compared with those with a glucose concentration of 144mgm/dL.(<8·0 mmol/l). This result suggests that 1-h postload glucose concentration may be a useful predictor for identifying people at high risk of developing diabetes mellitus even among those with normal glucose tolerance. This data suggest that β-cell dysfunction may be an early determinant of dysregulation of glucose metabolism within the normal glucose tolerance range and that a higher 1-h postload plasma glucose concentration denotes a defect in β-cell function in Koreans with normal glucose tolerance.

Based on the present study findings, we may be able to categorize subjects at high risk of diabetes mellitus using 1-h postload plasma glucose level. In this study, we suggested that 144mg/dL.(8 mmol/l) of 1-h postload glucose concentration is the most appropriate cut-off based on the Youden Index for predicting the incidence of diabetes mellitus in Koreans and possibly in other East Asians. The proposed cut-off value seemed to be lower than the data for Caucasian. This might be a result of Korean subjects having a lower β-cell reserve at the same glucose levels when compared with Caucasians.

The cut-off value for 1-h postload plasma glucose concentration was 144mg/dL.(8·0 mmol/l) in the study, which is lower than the concentration of 155mg/dL.(8·6 mmol/l) reported in Caucasian studies.

Practice Pearls:

  • This is the largest community-based epidemiological study to investigate the role of 1-h postload glucose concentration in risk stratification for future diabetes mellitus.
  • 1-h postload plasma glucose concentration was found to be related to cardiovascular risk factors such as hypertension and dyslipidemia.
  • The mean time of progression to diabetes mellitus was 6·8 ± 3·3 years.

Clin Endocrinol. 2017;86(4):513-519.