REN and diabetes mellitus: Patients with diabetes mellitus, especially those with chronic kidney disease (CKD), are prone to disorders of potassium metabolism, especially hyperkalemia due to the progression of renal disease or the use of renin-angiotensin-aldosterone blockers, and also in diabetic patients themselves in the hyperglycemic state, where the polyol pathway is activated, leading to intracellular accumulation of sorbitol, which in turn leads to peripheral neuropathy and the consequent elevation of serum sNfL.