Elevated haemoglobin A1c but not fasting plasma glucose conveys risk of chronic kidney disease in non-diabetic individuals.

Aims: To compare impact of elevated HbA1c and fasting plasma glucose (FPG) on incident chronic kidney disease (CKD) in a non-diabetic cohort.

Methods: Data from diabetes- and CKD-free 25,109 health examinees were retrospectively analysed with a mean observation period of 5.3 years. Prediabetes was diagnosed by the ADA and WHO criteria, and CKD by estimated glomerular filtration rate (eGFR) < 60 ml/min/1.73 m and/or dipstick proteinuria. Cox proportional hazards model was applied with sex, age, insulin sensitivity, systolic blood pressure, eGFR and serum alanine aminotransferase level as covariates.

Results: For incident CKD (n = 2483), high HbA1c but not FPG was an independent risk: adjusted hazard ratio (AHR, 95%CI) for HbA1c 1% and FPG 1 mmol/L, 1.91 (1.70-2.16) and 0.85 (0.60-1.20), respectively. Prediabetes by the ADA and WHO criteria were both risk for CKD with AHR (95%CI), 1.21 (1.12-1.32) and 1.31 (1.16-1.48), respectively. Prediabetes diagnosed by 'elevated HbA1c irrespective of FPG', either by the ADA and the WHO definition, was a risk with AHR (95%CI), 1.48 (1.36-1.61) and 1.51 (1.31-1.74), respectively. In contrast, prediabetes diagnosed by 'raised FPG irrespective of HbA1c' was not a CKD risk.

Conclusions: Elevated HbA1c, but not FPG, identified CKD risk in non-diabetic individuals.