Moderate salt restriction promotes the antialbuminuric effect of losartan in patients with type 2 diabetes and macroalbuminuria, a recent study showed.
For their study, the researchers evaluated patients with type 2 diabetes, 24-hour albuminuria of more than 300 mg despite 100 mg daily losartan therapy, blood pressure (BP) of less than 140/90 mm Hg, and serum creatinine concentration of less than 2 mg/dL.
Patients were randomly assigned to a high-sodium (more than 200 mEq [4.8 g] per day) or low-sodium diet (less than 100 mEq [2•4 g] per day) diet. Patients were also assigned to treatment with oral paricalcitol (2 μg per day) for 1 month and placebo for 1 month, or placebo for 1 month followed by paricalcitrol for 1 month.
Results showed that 24-hour albuminuria was reduced by 36.6% in the low-sodium group, but did not change significantly in the high-sodium group (2.9% increase), resulting in a 32.4% difference between groups that correlated with changes in natriuresis.
Paricalcitrol treatment mitigated the increase in salt-induced albuminuria by 17.8% in patients on the high-sodium diet, whereas it did not have a significant effect in those on the low-sodium diet vs placebo. Placebo resulted in an albuminuria decrease in the low-sodium group, but did not change significantly in the high-sodium group.
The researchers noted that treatment was well-tolerated, with 67 adverse events occurring in 52 (45%) patients during paricalcitrol treatment and 44 events occurring in 36 (31%) patients during placebo treatment. No patients died throughout the course of the study.
“In patients with macroalbuminuria and type 2 diabetes, moderate salt restriction enhances the antialbuminuric effect of losartan, an effect that could be nephroprotective and cardioprotective in the long term,” the researchers concluded.
Parvanova A, Trillini M, Podestà MA, et al; the PROCEED Study. Moderate salt restriction with or without paricalcitol in type 2 diabetes and losartan-resistant macroalbuminuria (PROCEED): a randomised, double-blind, placebo-controlled, crossover trial. The Lancet Diabetes Endocrinol.2018;6(1):27-40.