American Diabetes Association's 73rd Scientific Sessions:
Carb Counting May Not Deliver Vast Glycemic Improvement
Carbohydrate counting is standard dietary strategy for people with type 1 diabetes. Yet, a new meta-analysis suggests that the practice does not have a significant effect on blood glucose control.
In the meta-analysis, researchers led by Kirstine Bell evaluated 6 randomized controlled trials of interventions lasting at least 3 months. The trials compared carbohydrate counting with general or alternate dietary advice. Five of the studies were conducted in a total of 563 adults, and one was conducted in 104 children aged 8 to 13 years.
Ms. Bell, a PhD candidate at the University of Sydney, Australia, reported that when compared with control or alternate advice, there was a non-significant decrease in HbA1c of 0.3% points. In adults only, there was a decrease of 0.4% points, which the researchers considered marginally significant. All 6 studies suggested a decreased risk of hypoglycemia in patients who used carbohydrate counting, but only 4 of the 6 studies favored the strategy over control or alternate advice.
In her presentation, Ms. Bell speculated that health literacy might play a role in the effectiveness of the strategy. “Carbohydrate counting requires numeracy and literacy skills not all [patients] may have,” she said, noting that there may be increased reliance on less healthful, prepackaged foods because the labeling lists carbohydrate values. The study in children suggested susceptibility to making poor food choices among adolescents because of a belief that carbohydrates are “bad” and fats and proteins are “good,” she added.
Melinda Maryniuk, MEd, RD, CDE, Director, Clinical and Education Programs at Joslin Diabetes Center in Boston, agreed that there might be challenges in how carbohydrate counting is used.
“While its simplicity has been helpful for many individuals compared to former meal-planning methods, where up to 6 groups of foods were counted—meat, fruit, breads, milk, vegetables, and fat—carbohydrate counting also has its limitations,” Ms. Maryniuk told EndocrineWeb. “Individuals can be so focused on counting carbs that they neglect the overall caloric impact of a meal. For example, a breakfast of oatmeal and milk as compared to one of oatmeal, milk, eggs, and bacon will have the same amount of carbohydrates, but the second breakfast is much higher in calories, protein, and fat.”
In selecting research for the analysis, the Australian team initially reviewed 294 potentially relevant studies. That such a small percentage of those studies met the criteria for inclusion in the meta-analysis is telling, said Ms. Bell. “It’s concerning that there are only 6 studies that could be identified when this is such an integral element of diabetes management in type 1 diabetes. It affects the management of millions of people around the world.”
“There is limited evidence to support carbohydrate counting over other dietary interventions for improving glycemic control in type 1 diabetes,” Ms. Bell said. “But that doesn’t mean we should abandon carbohydrate counting. It’s still the best method, but we need to research it further. We may need to have more realistic expectations about the improvement in glycemic control.”
Ms. Maryniuk agrees. “Conducting well-designed nutrition research studies are essential to evaluating meal-planning approaches. When it comes to asking individuals with diabetes to modify eating behaviors, we want to make sure the evidence supports the change being recommended.”
Ms. Bell and Ms. Maryniuk disclosed no conflicts of interest.