The findings of a new study indicate that a diet high in carbohydrates can moderately raise blood pressure (BP) in patients with type 2 diabetes. The study compared the effect of 2 same-calorie diets: one high in carbohydrates (55% of calories) and one lower (40% of calories). Forty-two patients with type 2 diabetes were studied for two 6-week periods, one period on each diet, with a 1-week break in between. Patients were then invited to continue the second diet for an additional 8 weeks. Thirteen patients continued eating the high-carb diet, while 8 stayed on the low-carb diet.
At the end of the 8-week extension, the high-carb diet was associated with a diastolic BP that was 7 points higher than at the end of the initial 6-week phases; systolic BP was 6 points higher in this group, and heart rate was higher by 7 to 8 beats per minute.
In contrast, the low-carb diet group showed a significant lowering of heart rate, compared with the end of the 6-week phases, and both BP measurements were 3 to 4 points lower after a total of 14 weeks on the low-carb diet.
According to researchers from the University of Texas Southwestern Medical Center at Dallas, "the most plausible mechanism for an increase in BP and heart rate on a high-carbohydrate diet might be the accentuation of high insulin levels." The findings were reported in the November issue of Diabetes Care.