Risk of progression to diabetes from prediabetes defined by HbA1c or fasting plasma glucose criteria in Koreans.

AIMS

To examine the abilities of HbA1c and fasting plasma glucose (FPG) criteria predicting 5-year progression rate to diabetes in Korean adults with prediabetes.

METHODS

Participants included 17,971 Koreans (aged 20-79years) who underwent routine medical check-ups at a mean interval of 5.2years (3.1-6.7years). Prediabetes was defined as FPG 5.6-6.9mmol/l or HbA1c 5.7-6.4% (39-46mmol/mol). Incident diabetes was defined as FPG⩾7.0mmol/l, HbA1c⩾6.5% (48mmol/mol), or initiation of antidiabetic medications.

RESULTS

At baseline, the prevalence of prediabetes was 30.6% (n=5495) by FPG and 20.4% (n=3664) by HbA1c criteria. The 5-year progression rate to diabetes was significantly higher in prediabetes identified by HbA1c than by FPG tests (14.7% vs. 10.4%, P<0.001). Of individuals diagnosed with prediabetes by only one test, those by HbA1c alone had a higher risk of progression to diabetes than those diagnosed by FPG alone (6.0% vs. 3.9%, P<0.001). Receiver operating characteristic curve analysis showed that area under the curve was greater for HbA1c (0.855, 95% CI 0.840-0.870) than for FPG (0.830, 0.813-0.846) (P=0.016). After adjustment for conventional risk factors, the odds ratio (OR) of developing diabetes was higher in participants with prediabetes identified by HbA1c (OR 9.91, 8.24-11.9) than by FPG (OR 7.29, 5.97-8.89) (P=0.026).

CONCLUSIONS

Although fewer individuals with prediabetes were identified by HbA1c than by FPG criteria, the ability to predict progression to diabetes was stronger for HbA1c than for FPG in Koreans.