Fasting GLP-1 Levels and Albuminuria Are Negatively Associated in Patients with Type 2 Diabetes Mellitus

Glucagon-like peptide-1 (GLP-1) is an incretin hormone known for its pivotal role in enhancing insulin secretion and reducing glucagon release from the pancreas. Diabetic nephropathy, which is characterized by albuminuria, represents a significant microvascular complication of diabetes. Most of the previous studies mainly focused on the therapeutic renal protective effect in clinical trials after the administration of GLP-1 receptor agonists (GLP-1 RAs), rather than before administration. Hence, this study aimed to investigate the association between fasting plasma GLP-1 levels and albuminuria before GLP-1 RA administration. A cross-sectional study was designed to evaluate the association between fasting plasma GLP-1 levels and albuminuria in patients with type 2 diabetes mellitus (T2DM). A cohort of 68 participants with T2DM was analyzed using data collected at Wonkwang University Hospital in Iksan, Korea. Logistic regression analysis was employed to determine the odds ratio (OR) and 95% confidence interval (CI) of the incidence of albuminuria between two groups categorized by fasting GLP-1 levels, low (Group L) and high GLP-1 (Group H). The OR (95% CI) for the incidence of albuminuria comparing Group L with Group H of fasting plasma GLP-1 levels was 3.41 (1.16-10.02), p = 0.03 after adjustment for relevant variables including age, gender, fasting plasma glucose, HbA1c, C-peptide, creatinine, and medication use [angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs), sodium-glucose cotransporter-2 (SGLT-2) inhibitors, and dipeptidyl peptidase-4 (DPP-4) inhibitors]. When analyzed as a continuous variable, each 1 pmol/L reduction in fasting plasma GLP-1 levels was associated with an OR (95% CI) of 1.67 (1.17-1.87), p = 0.02, following full adjustment. These results highlight a negative association between fasting plasma GLP-1 levels and the incidence of albuminuria in Korean patients with T2DM, before GLP-1 RA administration. These findings suggest that endogenous GLP-1 may have a beneficial impact in mitigating albuminuria.