High Carb Diet May Up Blood Pressure In Diabetics
NEW YORK (Reuters Health) - In patients with type 2 diabetes, 14
weeks of a high-carbohydrate diet modestly raises blood pressure
compared to a diet high in monounsaturated fat, new study findings
indicate.
Studies evaluating the effects of high-carbohydrate and high-
monounsaturated fat diets have yielded conflicting results, Dr.
Abhimanyu Garg and colleagues note in their report, published in the
journal Diabetes Care. They suggest that these studies may have been
limited by their short duration.
Their own study compared the effect of two same-calorie diets: a high-
carbohydrate diet consisting of 55 percent of calories as
carbohydrate, 30 percent as fat, and 10 percent as monounsaturated
fat; and a high-monounsaturated fat diet deriving 40 percent of
calories from carbohydrate, 45 percent from fat, and 25 percent from
monounsaturated fat.
The 42 patients with type 2 diabetes participating in the study
consumed each diet for 6 weeks, with about 1 week between the two
periods, with the order of the diets randomly assigned. Subjects were
invited to continue the second diet for an additional 8 weeks. Eight
patients continued on the high-monounsaturated fat diet and 13
continued on the high-carbohydrate diet.
Garg, from the University of Texas Southwestern Medical Center at
Dallas, and his associates found that, after the initial 6-week
periods, there were no significant differences between diets in
systolic or diastolic blood pressure, the upper and lower numbers on
a standard reading, respectively, or in heart rate.
However, after the 8 week-extension, the high carbohydrate diet was
associated with a diastolic blood pressure that was 7 points higher
than at the end of both 6-week phases, systolic blood pressure was 6
points higher, and heart rate was higher by 7 to 8 beats per minute.
In contrast, the 8-week extension of the high-monounsaturated fat
diet led to a significant lowering of heart rate compared with the
end of the initial 6-week periods. Systolic and diastolic blood
pressure were 3 to 4 points lower after 14 weeks on the high-
monounsaturated fat diet, but the difference did not reach
statistical significance.
"The most plausible mechanism for an increase in blood pressure and
heart rate on a high-carbohydrate diet compared with a high-
monounsaturated fat diet might be the accentuation of" high insulin
levels, the authors propose.
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