Objective: To explore the characteristics of 24-hour urinary electrolyte excretion in patients with type 2 diabetes mellitus (T2DM), and its correlation with urinary albumin and early renal injury.
Methods: A total of 1475 T2DM and 265 nondiabetic patients (ND group) from 2018 to 2020 were enrolled. According to the urinary albumin excretion rate (UAER), T2DM patients were divided into normal albuminuria group (NA group): UAER < 30mg/24h; Microalbuminuria group (MA group): UAER 30~300 mg/24 h; massive albuminuria group (PR group): UAER > 300mg/24h. The characteristics of 24h urinary electrolyte excretion in different groups were observed and the correlation between 24h urinary electrolyte excretion and urinary albumin was analyzed.
Results: We found that 24h urinary potassium, sodium, chlorine, phosphorus and magnesium in all subgroups of T2DM were higher than those in ND group (P < 0.001), 24h urinary calcium in ND group was higher than that in PR group (4.3±2.1 vs. 3.2±2.5, P < 0.001), but lower than that in NA group (4.3±2.1 vs. 4.7±2.8, P < 0.001). As urinary albumin increased, 24h urinary calcium of T2DM patients showed a decreasing trend while the other urinary electrolytes showed an increasing trend (P < 0.001). Urinary albumin was positively correlated with 24h urinary potassium, sodium, chlorine, phosphorus, magnesium (r=0.133~0.169, P < 0.001) and negatively correlated with 24h urinary calcium (r= -0.130, P < 0.001). Multiple linear regression showed that 24h urinary potassium was an independent influencing factor of urinary albumin (β = 0.178, P < 0.001).
Conclusion: There is a difference in 24h urinary electrolyte excretion between T2DM and nondiabetic patients. The urinary electrolyte excretion of T2DM patients varies with urinary albumin. 24h urinary electrolyte excretion changes before the appearance of albuminuria, which may be an indicator of early renal injury. High urinary potassium may serve as a parameter to predict early diabetic nephropathy.
Y. Wang: None. M. Zhang: None. H. Li: None. S. Qu: None.