High carb diet may up blood pressure in diabetics

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High carb diet may up blood pressure in diabetics

Thu Nov 24, 8:52 AM ET

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.

SOURCE: Diabetes Care, November 2005.