Diabetic cardiovascular complications are associated with up to 50% mortality, and current therapies are not effective enough. Renin–angiotensin–aldosterone system inhibitors (RAASis) are the standard of care for diabetic patients with hypertension and albuminuria. Based on our previous studies reporting the renoprotective effects of low-dose RAASis, here, we hypothesized that low-dose RAASi treatment has cardioprotective and antifibrotic benefits in type 1 diabetes mellitus (T1DM). After five weeks of T1DM, adult male Wistar rats received low doses of ramipril, losartan, or eplerenone for two weeks. Heart rate, blood pressure, and pulse wave velocity (PWV) were recorded. Aortic intima–media thickness (IMT), collagen accumulation, and myocardial fibrosis were assessed. All RAASis reduced PWV elevation, prevented the progression of myocardial fibrosis, and normalized B-type natriuretic peptide, troponin I, and fibroblast growth factor 23 levels without affecting blood pressure. Interestingly, only eplerenone reversed the decline in Klotho levels and reduced IMT and fibrosis in the media of the aorta. Our comparative analysis suggests that mineralocorticoid receptor antagonists, particularly eplerenone, may offer superior efficacy in halting both the arterial and the myocardial injuries in T1DM compared to angiotensin-converting enzyme inhibitors or angiotensin II type 1 receptor blockers.

Diabetic kidney disease (DKD) is the leading cause of chronic kidney disease. Current treatments for DKD do not halt renal injury progression, highlighting an urgent need for therapies targeting key disease mechanisms. Our previous studies demonstrated that activating the Sigma-1 receptor (S1R) with fluvoxamine (FLU) protects against acute kidney injury by inhibiting inflammation and ameliorating the effect of hypoxia. Based on these, we hypothesized that FLU might exert a similar protective effect in DKD. Diabetes was induced in male Wistar rats using streptozotocin, followed by a seven-week FLU treatment. Metabolic and renal parameters were assessed along with a histological analysis of glomerular damage and fibrosis. The effects of FLU on inflammation, hypoxia, and fibrosis were tested in human proximal tubular cells and normal rat kidney fibroblasts. FLU improved renal function and reduced glomerular damage and tubulointerstitial fibrosis. It also mitigated inflammation by reducing TLR4, IL6, and NFKB1 expressions and moderated the cellular response to tubular hypoxia. Additionally, FLU suppressed TGF-β1-induced fibrotic processes and fibroblast transformation. These findings suggest that S1R activation can slow DKD progression and protect renal function by modulating critical inflammatory, hypoxic, and fibrotic pathways; therefore, it might serve as a promising novel drug target for preventing DKD.