Serum bicarbonate not independently linked to renal, CV events in diabetic nephropathy

Serum bicarbonate was not independently associated with renal or cardiovascular endpoints among a cohort of patients with type 2 diabetes and nephropathy, according to research presented at the 50th European Association for the Study of Diabetes Annual Meeting.

“Chronic kidney disease comes with various consequences and complication,” Elise Schutte, MD, a PhD student of endocrinology/nephrology at the Kidney Center of the University Medical Center Groningen in the Netherlands, said during her presentation. “One of these complications is metabolic acidosis measured as a low serum bicarbonate. Metabolic acidosis, in its turn, also has several complication in the human body. Among those are muscle wasting, bone disease, reduced insulin sensitivity, reduced albumin synthesis and exacerbation of renal failure. Now this last one puts patients at risk for a vicious cycle of CKD, metabolic acidosis and further renal function decline.”

Elise Schutte

Schutte and colleagues evaluated 2,628 patients (65% male; mean age, 60 years) with type 2 diabetes and nephropathy with available baseline serum bicarbonate levels to determine whether serum bicarbonate is associated with renal and CV endpoints and mortality. Participants were divided into serum bicarbonate quartiles (<21 mEq/L, n=602; 22-23 mEq/L, n=497; 24-26 mEq/L, n=841; and >27 mEq/L, n=688). Endpoints measured included end-stage renal disease, CV events (both fatal and nonfatal) and mortality.

Overall, significant associations were found between serum bicarbonate and age (P<.05), diuretic use (P<.05), total cholesterol (P<.05), potassium (P<.05), chloride (P<.05), phosphate (P<.05) and estimated glomerular filtration rate (P<.001). Thirty-six percent of patients developed end-stage renal disease at follow-up, followed by 28% who developed ESRD or doubling of serum creatinine, and 17% who experienced a CV event. A negative association was found between serum bicarbonate and incident ESRD (HR=0.91; 95% CI, 0.9-0.93) and incidence of combined endpoint of ESRD or doubling of serum creatinine (HR=0.94; 95% CI, 0.92-0.96). However, significance was lost after adjustment for eGFR. Similar results were found among the two lowest quartiles groups, with significance being lost with adjustment for eGFR.

Associations were not found between serum bicarbonate and CV outcome.

“To conclude, I have showed … that serum bicarbonate is not an independent risk factor for endpoints in patients with type 2 diabetes and nephropathy,” Schutte said. “Further research is needed to find if CKD patients benefit from bicarbonate suppletion.”

For more information:

Schutte E. Abstract #8. Presented at: 50th EASD Annual Meeting; Sept. 16-19, 2014; Vienna.

Disclosure: Schutte reports no relevant financial disclosures.