A new study conducted in Japan by Hirohito Sone, MD, PhD, of Niigata University found that 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).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).

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.

Even though guidelines for diabetes care recommend reducing salt intake, the evidence so far has been based on studies of people without diabetes. This study establishes a clear relationship.The mean dietary salt intake ranged from 2.8 g in the lowest quartile to 5.9 g in the highest quartile (current daily goals for sodium intake are 1.5 g per day in the U.S., 2.36 g per day in Europe, and 3.9 g per day in Japan).

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 non-significant HR 1.58). 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.However, Overt nephropathy, diabetic retinopathy, and all-cause mortality were not significantly associated with sodium intake.

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