Endocrine Abstracts

Background: The predictive ability of prediabetes defined by HbA1c (5.7–6.4%) or fasting plasma glucose (FPG) criteria (5.6–6.9 mmol/l) for the development of diabetes may differ according to ethnic groups, but only limited longitudinal data are available in Asians. We examined the progression rate to diabetes in Korean adults diagnosed as prediabetes according to these two criteria.

Methods: We analyzed data of 9432 Korean adults (age 20–79 years) who underwent regular health check-ups in 2005 (baseline) and in 2010 (follow up). After excluding patients with previously diagnosed diabetes (n=332) and those with FPG ≧7.0 mmol/l or HbA1c ≧6.5% (n=353) at baseline, 8747 subjects (5706 men and 3041 women) were included for the analysis.

Results: Among the 8747 participants without diabetes at baseline, 3493 individuals (39.9%) were categorized as prediabetes. Among them, 1318 individuals (15.1%) met HbA1c criteria only (HbA1c only group), 1229 (14.1%) met FPG criteria only (FPG only group), and 946 (10.8%) met both criteria (both group). After 5 years, a total of 356 subjects (4.1% of total participants) converted to diabetes. Only 0.3% (17/5254) of subjects who had normal baseline FPG and HbA1c developed diabetes during 5 years. The 5-year incidence of diabetes was 3.5% (43/1229) for the FPG only group, 4.9% (65/1318) for the HbA1c only group, and 24.4% (231/946) for the both group. Multiple logistic regression analysis showed that age, sex-adjusted odds ratios (ORs) for the FPG only, HbA1c only, and both groups were 10.7 (95% CI, 6.0–18.8), 15.8 (9.2–27.1), and 95.0 (57.3–157.4), respectively. After further adjustments for smoking, alcohol drinking, exercise habits, body mass index, waist circumference, systolic blood pressure, hemoglobin, cholesterol, HDL-cholesterol, and triglycerides levels, ORs for the FPG only, HbA1c only, and both groups were 7.7 (95% CI, 4.3–13.9), 12.9 (7.5–22.3), and 69.8 (41.7–116.7), respectively.

Conclusion: Individuals categorized as prediabetes by both of the FPG and HbA1c criteria have substantially high risk for progression to diabetes, while those classified as normal by both criteria have very low risk in Koreans. Those who discordantly met only one criterion have intermediate risk, but HbA1c only group tends to have higher risk than FPG only group.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.