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High-salt Diet and High HBA1c May Increase Cardiovascular Disease

A synergistic effect may exist between HbA1c level and dietary sodium intake for the development of CVD…. 

Many studies have showed that dietary sodium restriction in patients with type 2 diabetes presented a modest reduction in blood pressure. Moreover, salt supplements reduced the efficacy of hypertensive efficacy of BP-lowering drugs. The American Diabetes Association recommends reducing sodium intake to 1.5 g/d, but only in patients who does not have diabetes. The correlation between dietary sodium intake and incidence of diabetic complications still remains uncertain.

A nationwide cohort study was conducted in Japan on patients with type 2 diabetes aged 40-70 years with A1C>6.5 from 59 university and general hospitals to examine the correlation between dietary sodium intake and incidence of diabetic complications. A total of 1,588 people responded to a survey about their diets with sodium intake and researchers looked at cardiovascular complications over eight years. Researchers divided all the participants into four different groups based on their sodium intake, 2.8 g in the lowest quartile to 5.9 g in the highest quartile. The original primary endpoints of the study were to look at microvascular and macrovascular complications due to diabetes. The patient groups were followed to see if they developed CVD, nephropathy or retinopathy.

Mean daily dietary sodium intake across quartiles ranged from 2.8 to 5.9 g. Patients in the highest quartile of salt consumption with A1C’s greater than 9% had double the risk of developing cardiovascular disease than those in lower quartiles who ate 2.8g of sodium daily on average (1.58 (0.81–3.07) and 16.14 (2.86 –91.19), P < .01). During the 8-year follow-up, incidents of cardiovascular from first to fourth quartiles of sodium intake were 23, 36, 32, and 41 for CVD.

Patients with uncontrolled diabetes showed doubled cardiovascular risk with higher consumption of dietary daily sodium consumption. Therefore, it is thought that there is synergistic effect between higher A1C level and dietary sodium daily intake for the progression of cardiovascular complications.

Practice Pearls:
  • Many guidelines recommend reducing dietary sodium intake in patients with diabetes.
  • This study of Japanese patients with type 2 diabetes discovered that patients who consumed average sodium of 5.9 g daily had about a 2-fold higher risk of CVD than those who consumed an average of 2.8 g daily.
  • The effects of a high-sodium diet were exacerbated by poor blood sugar control.

Horiakwa C, et al "Dietary sodium intake and incidence of diabetes complications in japanese patients with type 2 diabetes" J Clin Endocrinol Metab 2014; DOI: 10.1210/jc.2013-4315.