A normal and healthy blood pressure reading is lower than 120/80. According to the American Diabetes Association, two out of three people with type 2 diabetes (T2DM) have high blood pressure, or hypertension -- defined as a reading of 140/90 or higher. Even individuals with T2DM who do not currently have hypertension are still at increased risk for developing this condition. Obesity is common in T2DM, and other common disease mechanisms such as inflammation and insulin resistance can increase the risk of developing hypertension. Because sodium has a direct effect on blood pressure, reducing dietary sodium is the most common lifestyle recommendation a doctor may prescribe to help manage this condition.
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Sodium and Type 2 Diabetes
While many factors can lead to high blood pressure, dietary sodium plays an important role. Sodium is an essential dietary mineral and is needed to maintain fluid balance and send nerve impulses. Excess sodium can cause the body to retain more fluid, which can make the heart pump a higher blood volume. This causes increased pressure against the blood vessels and over time can cause damage to the blood vessels and heart, increasing the risk of common T2DM complications -- cardiovascular disease and stroke. In fact, according to the American Diabetes Association (ADA), two out of three people with diabetes die from heart attack or stroke, making it essential for anyone with diabetes to keep blood pressure under control.
The ideal sodium restriction for blood pressure management has recently been the subject of debate. ADA clinical practice guidelines published in the January 2014 "Diabetes Care" recommend a sodium intake for people with T2DM of less than 2,300 milligrams daily -- similar to the recommendations for the general public. The 2013 joint American Heart Association and American College of Cardiology practice guidelines recommend a similar sodium restriction -- less than 2,400 milligrams per day. However, both of these guidelines also address the fact that lower sodium intakes -- to 1,500 mg daily or less -- can achieve better blood pressure control. However according to ADA, this strict level is for individualized recommendations, not a universal guideline. Of note, the Institute of Medicine in a 2013 brief concluded that there was no added benefit to decreasing the daily amount of sodium significantly below 2,300 milligrams, and in some cases, drastic decreases were harmful to those with T2DM in terms of cardiovascular events and death from all causes.
How to Limit Sodium
One teaspoon of table salt contains just over 2,300 milligrams of sodium. Salt is not consumed by the teaspoon, therefore, it is helpful to learn about the sodium content of foods eaten daily, avoid adding salt to foods and identify sodium content via food labels. In a Western diet, processed foods are a major source of sodium. Restaurant meals, canned vegetables, frozen entrees and foods with a long shelf life often contain large amounts of sodium. Other hidden sources of sodium include cured meats, soy sauce, canned and dried soups and seasoning packets. A helpful strategy to keep sodium levels below the recommended level is to prepare foods at home, emphasizing fruit, vegetables, whole grains, nuts, seeds, low-fat or nonfat milk and yogurt, as well as lean protein foods such as dried beans, chicken, fish, tofu or lean meat. These foods, as part of a low sodium diet, are at the core of the DASH diet -- which successfully lowered blood pressure levels in the Dietary Approaches to Stop Hypertension Trial published in the January 2001 New England Journal of Medicine.
Warnings and Next Steps
In addition to sodium's role in blood pressure management, sodium may need to be limited for other health conditions. Sodium restriction is recommended for those with chronic kidney disease and congestive heart failure, because it can lead to fluid retention and limiting sodium helps reduce fluid volume. For guidance with diet for diabetes and blood pressure management, ask for a referral to a registered dietitian. Anyone with high blood pressure should also have regular blood pressure checks and keep track of the results. If lifestyle changes such as sodium reduction, weight loss or physical activity are not working to lower blood pressure, a doctor will determine the next course of action, which could include medication.