Eating high amounts of salt impairs glycemic control and predisposes to overweight and obesity, according to a new study from China reported in the journal Diabetes, Metabolic Syndrome and Obesity.

The study included 1145 patients, aged 51.4 years (mean), with type 2 diabetes. These patients were managed as outpatients between March 2018 to January 2020 at the National Standardized Metabolic Disease Management Center at Ningbo First Hospital in the Zhejiang province of China. Patients were asked to complete a questionnaire on food frequency and lifestyle. Intake of dietary salt was categorized into three groups: ≤6 g/day, 6–8 g/day (excluding 6g/d) and >8 g/day. Patients older than 75 years or younger than 18 years and pregnant/lactating women were excluded from the study. Patients with renal impairment (eGFR <30 mL/minute), liver dysfunction were also not included in the study group.

Results showed high levels of fasting and postprandial plasma glucose and HbA1c in all the three dietary salt groups. However, the association for fasting plasma glucose and HbA1c was particularly strong in persons who consumed >8 g of dietary salt in a day vs groups with lower salt intake (≤6 and 6–8 g/day). Compared to lower dietary salt (≤6 g/day), higher dietary salt (>8 g/day) increased FPG by around 42 mg/dL (2.3 mmol/L) and HbA1c by 0.67%.

Persons with higher dietary salt intake of >8 g/day were also more likely to be overweight and obese than those who consumed lower amounts of salt. They also had higher blood lipid levels.

After China, India has the second highest number of people living with type 2 diabetes (77 million). This number is projected to increase to 134 million by 2045. Diabetes remains undiagnosed in more than half of the population.

This study was undertaken with the objective to examine the relationship between dietary salt and plasma glucose and HbA1c levels in patients with type 2 diabetes. And it found a positive association between high dietary salt intake and fasting plasma glucose and A1c.

“People with diabetes may have increased salt appetite and reduced salt taste perception to account for the inability to adhere to low sodium intake.”² 

All patients with type 2 diabetes should be educated about the need to restrict their salt intake to improve long-term prognosis. Besides the need to reduce added salt, they should be especially informed about the sodium content of foods, which could be adding to the daily intake accounting for the higher intake, despite compliance with the recommendations.

The American Diabetes Association (ADA) recommends that people with diabetes should limit their sodium intake to less than 2300 mg per day. People with diabetes who have high blood pressure, chronic kidney disease, or those aged 50 years should further reduce their salt intake to 1500 mg/day. 

 Reference

1. Lin Y, et al. Association between dietary salt and plasma glucose, insulin and hemoglobin A1c levels among type 2 diabetes patients in Eastern China. Diabetes Metab Syndr Obes. 2021;14:4811-4818. https://doi.org/10.2147/DMSO.S338915.
2. Baqar S, et al. Dietary sodium and potassium intake in people with diabetes: are guidelines being met? Nutr Diabetes. 2020 Jun 17;10(1):23. doi: 10.1038/s41387-020-0126-5.