It is well established that low levels of high-density lipoprotein cholesterol (HDL-C) pose a significant risk for diabetic kidney disease (DKD) in patients with type 2 diabetes (T2D). However, the protective effect of higher HDL-C levels against the development of DKD has remained unclear. Recently, Chinese researchers conducted a study to explore this relationship further, shedding light on the role of HDL-C in DKD risk among individuals with T2D.

      This cross-sectional observational study randomly recruited T2D patients aged 18 and older. Patients with other kidney diseases, severe infections, inflammatory conditions, pregnancy, systemic immune diseases, tumors, severe cardiovascular or liver diseases, rapidly declining kidney function, or missing clinical data were excluded. The study aimed to provide a clear picture of how HDL-C levels impact DKD risk.

      The researchers recorded demographic details and measured various parameters, including fasting blood glucose, low-density lipoprotein cholesterol (LDL-C), HDL-C, triglycerides, total protein, serum albumin, uric acid, serum creatinine, blood urea nitrogen, urine albumin, and urine creatinine. The study population was divided into two groups: those with DKD and those without. Statistical analyses such as Pearson’s chi-squared tests, unpaired t-tests, and Mann–Whitney tests were used to compare the two groups.

      HDL-C levels were categorized into four quartiles: Q1 (0.40–0.96 mmol/L), Q2 (0.97–1.10 mmol/L), Q3 (1.11–1.31 mmol/L), and Q4 (1.32–6.27 mmol/L). Logistic regression analysis was performed to assess the relationship between HDL-C levels and DKD risk.

      Among the 936 participants with T2D, 309 (33.01%) had DKD. Significant differences in age, diabetes duration, hypertension, BMI, use of ACE inhibitors or ARBs, systolic blood pressure, triglycerides, uric acid, serum creatinine, and blood urea nitrogen levels were observed between the DKD and non-DKD groups. Compared to the lowest quartile of HDL-C (Q1), the DKD risk ratios for Q2, Q3, and Q4 were 0.63, 0.50, and 0.62, respectively, indicating that higher HDL-C levels were associated with a reduced risk of DKD (P-value for trend = 0.003). Interestingly, patients in the highest HDL-C quartile (Q4) had a slightly higher DKD risk compared to those in Q3.

      After adjusting for confounding factors such as age, sex, BMI, blood pressure, HbA1c levels, hypertension, and diabetes duration, the trend persisted, though the association was not statistically significant. The findings highlighted that low HDL-C levels increase DKD risk, and HDL-C levels greater than 1.54 mmol/L are significantly associated with increased DKD risk, particularly in women.

      This study underscores the complexity of the relationship between HDL-C levels and DKD risk in T2D patients. While higher HDL-C levels generally seem protective, very high levels may not confer additional benefits and could even pose a risk. These insights are crucial for better understanding and managing DKD risk in people with T2D.