- Many people with diabetes also have high blood pressure, as well as unique nutritional needs.
- One study found that reducing sodium intake and following a modified version of the DASH diet helped to decrease blood pressure in participants with type 2 diabetes.
- The main reason for the observed decrease in blood pressure was the decreased sodium intake.
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The dietary combination lowered systolic blood pressure among participants by around five points and diastolic blood pressure by around two points compared to the comparison diet with more sodium. This result was mainly from the decreased sodium consumption.
The findings were published in
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However, the study notes that the DASH diet doesn’t consider the unique dietary needs of people with type 2 diabetes. So, researchers created the “Dietary Approaches to Stop Hypertension for Diabetes (DASH4D) diet,” which is similar to the DASH diet but considers what adults with type 2 diabetes need. For example, this diet was lower in carbohydrates than the typical DASH diet. Researchers tested how this diet, combined with decreased sodium intake, affected participants’ blood pressure.
This randomized clinical trial included 102 adults with type 2 diabetes whose systolic blood pressure was between 120 and 159 mmHg. Participants were designated as having type 2 diabetes if they had a hemoglobin A1C of 6.5% or greater, were taking medications for diabetes treatment, or both.
People were ineligible to participate in the study for a number of reasons, including having type 1 diabetes, if their A1C was over 9%, or if they were taking weight loss medications.
The average age of participants was 66 years. About two-thirds of participants used at least two medications to help lower blood pressure, and a little over half used at least two medications to lower blood sugar.
Researchers assigned participants to receive four diets in varying orders, each for five weeks. One was a DASH4D diet with low sodium, and another was the DASH4D diet but with higher sodium intake. The other two were comparison diets: one with lower sodium and one with higher sodium, and these diets were similar to the intake of adults with diabetes living in the United States. The participants were provided with the food for their assigned diets, and aside from allowed beverages, they were not supposed to eat food from other sources outside the study.
Participants did not lose weight throughout the study. Researchers measured systolic blood pressure during the last two weeks of each diet intervention. They kept track of adverse events among participants, such as any very high blood pressure levels.
Participants self-reported how well they stuck to their assigned diets, but researchers also did a 24-hour urine excretion test during the fourth or fifth weeks to look at sodium, creatinine, and potassium levels, which also was a way to test how well participants were following diet assignments.
The findings showed that the lowering of blood pressure mostly occurred during the first three weeks of participants following a diet.
The researchers found that the DASH4D diet with reduced sodium showed a better overall decrease in blood pressure versus the comparison diet that had higher sodium intake. The average difference in systolic blood pressure between these two groups was 4.6 mmHg, and the average difference in diastolic blood pressure was 2.3 mmHg.
“The main finding was that a low-sodium DASH4D diet (compared to a higher sodium typical American diet) caused a statistically and clinically significant reduction in blood pressure. Sodium reduction appeared to contribute more strongly to reducing blood pressure than the DASH4D diet.”
— Scott J. Pilla, MD
Jennifer Wong, MD, a board-certified cardiologist and medical director of Non-Invasive Cardiology at MemorialCare Heart and Vascular Institute at Orange Coast Medical Center in Fountain Valley, CA, also noted that “Studies like these remind us of the beneficial impact of a heart-healthy diet, especially a low salt diet designed to modify blood pressure.”
This research only included a small number of participants and focused on a niche subgroup of individuals, limiting generalizability. The majority of participants were Black, which provided important information about this at-risk group. Two-thirds of the participants were women. However, research in other groups may also be helpful.
The dietary interventions for this study each only lasted five weeks, so long-term follow-up may be helpful with further research.
Some data, such as following the assigned diet and health history, was self-reported by participants, so inaccuracies are possible.
While adverse events on the DASH4D diet with low sodium were low, more research into the potential risks may be helpful. Researchers also suggest the need for more research in people with a higher level of risk. The amount that blood pressure was lowered by could have been less in this study for many reasons, such as the high number of participants taking diuretics and the number of participants who experienced changes to their blood pressure medications during the study.
Researchers acknowledge that they weren’t able to detect the separate impact of the DASH4D diet and decreased sodium intake. Another struggle was the COVID-19 pandemic. The authors explain that this “interrupted participant feeding at several points.” It was also only a single-site study.
Pilla also noted that “More work is needed on how to make Healthy, low sodium diets accessible. Following a Healthy diet can be challenging and costly, and we would like to design diets that meet the DASH4D nutrient targets that are more affordable and tailored to different cultures.”
Researchers note that it may be hard to decrease sodium intake to only 1,500 mg a day, and future research in this area will be helpful. The authors say this research should include “implementation research in community settings.”
The result suggests that the DASH4D eating plan combined with lower sodium intake helps with blood pressure reduction in people with type 2 diabetes. Researchers note that a five mmHg reduction in systolic blood pressure can decrease the risk of stroke, heart failure, and cardiovascular events. It can also help with kidney outcomes.
Pilla noted the following regarding the clinical implications of the study:
“Diet change can effectively improve blood pressure in people with diabetes, even those on multiple antihypertensive medications, so clinicians should still focus on diet even in these individuals.”
“Dietary sodium reduction is an important part of dietary change in people with diabetes to achieve better blood pressure control. Our specific DASH4D diet with lower sodium now has strong evidence for benefiting people with diabetes, so it should be strongly considered as a recommended diet in this population.”
— Scott J. Pilla, MD
Even though there may be a need for more research, Patrick Kee, MD, PhD, a cardiologist at Vital Heart & Vein, noted the following about the study’s results:
“The acceptability and adherence to the lower sodium intake (~1500 mg/day) was high among participants, suggesting that with proper guidance and access to prepared meals or education, such dietary targets are feasible in practice. This finding counters a long-standing belief that stringent sodium targets may be unrealistic for patients.”
