A saltier diet might boost the cardiovascular risk from type 2 diabetes, according to Japanese researchers.

The highest quartile of sodium intake was associated with 2.07-fold higher risk of cardiovascular disease than seen in the lowest quartile (95% CI 1.16 to 3.71), Hirohito Sone, MD, PhD, of Niigata University in Japan, and colleagues found. Within the Japanese cohort of people with hemoglobin A1c levels of at least 6.5%, each 1-g per day increase in sodium intake was associated with a 20% higher risk of heart and vascular disease (P=0.02), The research was published in the Journal of Clinical Endocrinology & Metabolism.

These results "show that high dietary sodium intake is associated with an elevated incidence of cardiovascular disease in patients with type 2 diabetes, which supports current guidelines for patients with diabetes," the researchers concluded.

Sone and colleagues looked at data from 1,588 patients over eight years of follow-up in the Japan Diabetes Complication Study, which involved 59 university and general hospitals in Japan. The prospective study set out to investigate the incidence of, and risk factors for macrovascular and microvascular complications of diabetes.

The mean dietary salt intake ranged from 2.8 grams in the lowest quartile to 5.9 grams in the highest quartile. When broken down by levels of blood sugar control, risk was dramatically elevated for patients in the top quartile of salt consumption compared with the bottom quartile if they had an HbA1c greater than 9% (HR 16.14 versus a nonsignificant HR 1.58). Risks of nephropathy, diabetic retinopathy, and all-cause mortality, however, weren't associated with sodium intake.