A diet high in salt increases the risk of cardiovascular disease (CVD) in patients with Type 2 diabetes, show data from the Japan Diabetes Complications Study (JDCS).
The finding “supports current guidelines for patients with diabetes”, say researcher Hirohito Sone (Niigata University Faculty of Medicine, Japan) and co-workers. They note that effect of dietary sodium on diabetic complications has been little studied, despite the existence of guideline recommendations to limit salt intake in diabetic patients.
There were 1588 JDCS patients with baseline dietary information available; they were about 59 years old at baseline and were followed up for 8 years. The incidence rates of diabetic complications during this time were 13.61, 8.70, and 42.49 per 1000–years for CVD, overt nephropathy and diabetic retinopathy, respectively, and the mortality rate was 6.68 per 1000–years.
After adjusting for variables including age, glycated haemoglobin (HbA1c) levels, lipid profiles and blood pressure, patients in the top quartile of daily sodium intake were a significant 2.17-fold more likely to have a CVD event than patients in the bottom quartile. By contrast, sodium intake was not associated with the risk of nephropathy and diabetic retinopathy.
Of note, there was a significant interaction between sodium intake and HbA1c levels, such that the CVD risk associated with high salt intake was significantly higher among patients with HbA1c levels of 9% or higher than in patients with lower levels.
Specifically, there was no significant CVD risk increase among patients in the top versus the bottom quartile of sodium intake who had HbA1c levels below 9%, whereas there was a significant 9.91-fold increase among those whose with higher HbA1c levels.
“This finding indicated that a long-term reduction of dietary sodium intake is particularly important in those with poorly controlled blood glucose”, writes the team in the Journal of Clinical Endocrinology & Metabolism.
The researchers note that daily sodium intake among patients in the lowest quartile, at 2.8 g, was higher than that recommended in European and US guidelines, at 2.36 and 1.5 g, respectively, but lower than the recommended limit in Japanese guidelines, at 3.9 g.
On the other hand, these patients had a low overall rate of CVD events, at 6.5%, compared with 11.4% among patients in the top quartile, whose daily sodium intake averaged 5.9 g.
Nonetheless, the team concludes that “dietary salt restriction as medical nutritional treatment would be useful to prevent complications of diabetes in patients with type 2 diabetes.”
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