Conference Coverage
Counting carbs comes up short in type 1 diabetes
Major finding: The overall change in hemoglobin A1c levels with a variety of carbohydrate counting methods was 0.3% points, compared with other...
CHICAGO – Women with gestational diabetes on a conventional low-carbohydrate, high-fat diet were more insulin resistant, and their infants had slightly higher rates of adiposity, than did with women who consumed a diet high in complex carbohydrates and low in fat, according to a randomized pilot study of 11 women.
Both diets controlled maternal glucose and weight. "So, they’re both okay, except that tissue data and fasting levels imply that higher fat content is exacerbating insulin resistance during pregnancy," Teri L. Hernandez, Ph.D., said in an interview after presenting her findings at the annual scientific sessions of the American Diabetes Association.
Dr. Teri L. Hernandez
It’s too soon to tell if and when the findings will have implications on practice. "It’s a good study," said Dr. Assiamira Ferrara, senior research scientist at Kaiser Permanente, Oakland, Calif., who was a moderator and not involved in the study. "But we need a bigger sample size and more feasibility studies on whether women will adhere to the diet" before we try this outside of a research environment.
The conventional diet recommended to women who have gestational diabetes (GDM) has mainly focused on carbohydrate (CHO) restriction. But Dr. Hernandez and her colleagues said that the restrictions result in greater fat intake, which in turn could promote insulin resistance and increase fetal adiposity. Meanwhile, owing to patient noncompliance and a lack of controlled designs, evidence remains confounded, she reported.
In a recent unpublished systematic review of prospective, randomized, controlled trials of diet interventions in women with GDM, Dr. Hernandez and her colleagues found that women tolerated higher complex carb/low glycemic index diets and that diets higher in unrefined carbs effectively blunted postprandial glycemia, reduced the need for insulin therapy, and improved insulin sensitivity, hemoglobin A1c, and systolic blood pressure.
Dr. Hernandez of the departments of medicine and nursing at University of Colorado at Denver in Aurora, said that she has a larger number women in her ongoing study, but the findings so far "lend evidence to the idea that women can tolerate more carb than we thought.
"These women are worried about their baby’s outcome, and they’re afraid their babies are going to be born too big, so they become very fearful of carbohydrates. What this says is that they can actually have toast and other carbs in their diet and still have a great outcome, and it could even help improve their insulin resistance," she said in an interview.
Researchers randomized five women to the conventional low-carb/high-fat diet, and 6 women to the high-carb/low-fat diet.
The low-carb/high fat diet comprised 40% CHO, 45% fat, and 15% protein; the high-carb/low fat diet contained 60% CHO, 25% fat, and 15% protein. Simple sugars made up about 18% or less of total daily calories.
The subjects were rather healthy women with mild gestational diabetes, were highly compliant, and were closely matched, with a mean body mass index of 33.5 kg/m2, and were 29-30 years old. They were provided with all the meals.
During the study period, weight gain was similar in both groups, and their glycemic profiles were below target.
However, the high-carb/low-fat diet group had lower fasting glucose and fasting insulin at 6 and 7 weeks, compared with the low-carb/high-fat diet group (P = .007 and .06, respectively)
Results also showed that the postprandial free fatty acids were significantly higher in the low-carb/high-fat diet group (P = .037). And, at week 37, fasting glucose, insulin, and maternal insulin resistance (HOMA-IR) were significantly higher in the low-carb/high-fat diet, compared with the low-fat/high-carb diet (P = .007, .06, and .02, respectively).
Meanwhile, infant adiposity was slightly higher in the infants of the low-carb/high-fat groups, compared with the high-carb/low-fat group (14% v. 11%). And, regardless of diet, higher fasting insulin and HOMA-IR at 37 weeks were associated with greater infant adiposity (P less than .05).
Dr. Hernandez said that both diets are doing a good job, and thus far, there haven’t been any adverse outcomes because of either diet.
Dr. Hernandez had no disclosures. Dr. Ferrara is an employee of Takeda Global Research and Development and has received research support from Takeda Pharmaceutical.
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