Glycaemic and haemoglobin A1c thresholds for detecting diabetic retinopathy: the fifth Korea National Health and Nutrition Examination Survey (2011).

Abstract

AIMS: Few representative population-based data are available regarding glycaemic

and HbA1c thresholds for detecting diabetic retinopathy (DR) in Asia. We

investigated the association between DR and fasting plasma glucose (FPG) and

HbA1c levels among Korean adults. METHODS: Using data from the Korea National

Health and Nutrition Examination Survey (2011), a total of 5212 adults (>/=19

years old) were analysed. When participants had diabetes mellitus and/or a

suspicion of DR in two-field nonmydriatic fundus photography, seven standard

photographs were obtained after pupil dilatation (75.9% of men, 75.0% of women

among the subjects). DR was defined as the presence of >/=1 retinal

microaneurysms or blot haemorrhages with or without more severe lesions. Receiver

operating characteristic (ROC) curves were used to determine the optimal cut-off

value for HbA1c or FPG. RESULTS: The overall glycaemic thresholds for DR were

6.3mmol/l for FPG and 6.2% (44mmol/mol) for HbA1c. The optimal thresholds did not

differ by age group. The sensitivities and specificities were 82.6% and 91.2% for

FPG and 93.9% and 89.7% for HbA1c, respectively. The diagnostic discrimination

was better for HbA1c than FPG for DR-area under curve: 0.908 for FPG and 0.953

for HbA1c (p=0.007). After being controlled for other covariates, the odds ratio

for the risk of DR increased significantly in a consistent way from 6.2%

(44mmol/mol) for HbA1c and 6.3mmol/l for FPG. CONCLUSIONS: According to these

nationally representative data, the current diabetes diagnostic values for FPG

and HbA1c based on DR may be lower for the Korean population.