Glycated haemoglobin A1c is associated with low-grade albuminuria in Chinese adults

Diabetes is a strong risk factor for cardiovascular diseases, whereas few studies have investigated simultaneously the associations of glycated haemoglobin A1c (HbA1c), fasting blood glucose (fasting plasma glucose (FPG)) and 2 h postload blood glucose (2 h PG) with low-grade albuminuria, which is an earlier marker of cardiovascular diseases in the general population. Our study aimed to investigate and compare associations of HbA1c, FPG, and 2 h PG levels with risks of low-grade albuminuria in the middle-aged and elderly Chinese.

This was a cross-sectional study involving 9188 participants aged 40 years or older. All participants underwent a standard 75 g oral glucose tolerance test. Low-grade albuminuria was defined as the highest quartile of urinary albumin-to-creatinine ratio (ACR) (>6.10 mg/g in males and >8.76 mg/g in females) in respondents without microalbuminuria or macroalbuminuria.

HbA1c, FPG and 2 h PG were all significantly correlated with urinary ACR after adjustment for confounders (all p values <0.0001). After adjustment for HbA1c, the relationships of FPG and 2 h PG with ACR reduced to null. HbA1c levels were still significantly associated with ACR after further adjustment for FPG and 2 h PG. Multiple logistic regression showed that risks of low-grade albuminuria were positively associated with HbA1c levels in a dose-response manner. Compared with participants with HbA1c ≤ 37 mmol/mol (5.5%), ORs (95% CIs) for low-grade albuminuria were 1.05 (0.94 to 1.18), 1.25 (1.04 to 1.50), 1.40 (1.04 to 1.90) and 2.21 (1.61 to 3.03) for HbA1c categories of 38-42 mmol/mol (5.6-6.0%), 43-48 mmol/mol (6.1-6.5%), 49-53 mmol/mol (6.6-7.0%), and >53 mmol/mol (7.0%), respectively (p for trend <0.0001).

HbA1c, but not FPG or 2 h PG, was independently associated with an increased risk of low-grade albuminuria in the middle-aged and elderly Chinese.