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Nutrition experts debate merits, risks of low-carb diets in pediatric type 1 diabetes patients


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6 minutes

Belinda S. Lennerz, MD, PhD
Belinda S. Lennerz, MD, PhD

During a virtual debate at this year’s Scientific Sessions, pediatric endocrinologist Belinda S. Lennerz, MD, PhD, demonstrated the benefits of carbohydrate restriction in adolescents with type 1 diabetes, while Carmel E. Smart, RD, PhD, argued that patients can achieve comparable glycemic control with less restrictive diets and less risk.

The symposium, Low-Carb Diets in Pediatric Type 1 Diabetes—Pros and Cons, can be viewed by registered meeting attendees at through September 10, 2020. If you haven’t registered for the Virtual 80th Scientific Sessions, register today to access all of the valuable meeting content.

“Before insulin, very low-carb diets were used to prolong life,” said Dr. Lennerz, Attending Physician at Boston Children’s Hospital. “Even after [insulin was introduced], carbohydrate intake stayed low for many years.”

Dr. Lennerz defined a low-carb diet as less than 50 grams of carbohydrates per day, or less than 10% of daily calories from carbohydrates. Some diets may also limit protein to achieve ketosis.

“As [low-carb diets] gain in popularity in the general population, they also gain interest in the diabetes community,” said. Dr. Lennerz, who described several reasons why low-carb diets appeal to some diabetes patients—beginning with glycemic variability.

Carmel E. Smart, RD, PhD
Carmel E. Smart, RD, PhD

“Postprandial glycemic variability is important because it contributes significantly to overall glycemic control and is an independent cardiovascular risk factor,” she said. “Postprandial glycemic variability is largely caused by carbohydrate intake. In addition, children and adults with type 1 diabetes are at risk of [being] overweight and metabolic syndrome. We know that higher insulin doses are associated with weight gain, potentially due to extra carbohydrate intake to treat hypoglycemia, or because of anabolic insulin effects.”

Dr. Lennerz reviewed survey data from a group that promotes a very low-carb diet based on the book Dr. Bernstein’s Diabetes Solution. Dr. Lennerz’s team conducted an online survey of 316 patients with physician participation to corroborate the data. Of the participants, 42% were children with an average daily carbohydrate intake of 16 grams a day. Participants had been on a low-carb diet an average of 2.2 years.

“The most striking finding here is the average A1C was 5.67%, which is really unprecedented in type 1 diabetes,” she said. “Moreover, almost all of the patients were able to achieve their glycemic target as recommended by the ADA. They had low glycemic variability and they had a fairly low insulin requirement.”

Survey participants reported few diabetes-related complications, with only 1% reporting a diabetic ketoacidosis event and 1% reporting a hypoglycemic event. Dr. Lennerz said the researchers did find slightly elevated lipids among respondents, but patients also had high levels of high-density lipoprotein cholesterol and low triglycerides.

In her rebuttal, Dr. Smart said a low-carb diet is not necessary to achieve good glycemic control and highlighted the risks associated with these diets.

“A lot of people believe that low carb means high protein, but it really means high fat,” said Dr. Smart, Senior Diabetes Dietitian at John Hunter Children’s Hospital in Newcastle, Australia. “We know from published literature that as carbohydrate intake decreases, dietary fat intake increases.”

Another concern, she said, is the absolute focus on carbohydrate amount.

“In this model, the message is all carbs are the same,” she said. “An apple is not a doughnut. These diets do not consider the impact of carb type on glycemia. In a study we published, we found the type of carb has a significant impact on glucose level. In addition, fat and protein also cause high blood glucose levels.”

Low carb does not equate to a healthy eating pattern, added Dr. Smart, noting that low-carb diets exclude foods, increase red and processed meat intake, provide inadequate energy intake, elevate lipids, and put patients at risk for nutritional deficiencies, including B vitamins, iron, zinc, calcium, and fiber.

“It’s possible to match insulin to glycemic rises,” Dr. Smart said. “Glycemic targets are achievable with a usual carb diet. The key is to educate parents to establish habits children can use throughout their lives.”

To demonstrate this, Dr. Smart presented results from a paper her team published in 2019 that looked at dietary intake and eating patterns of 22 children in her clinic.

“We saw no association between A1C and carbohydrate intake,” she said. “Where we did see an association was between A1C and pattern of eating. If patients grazed all day and dosed postprandially, indeed, their A1C would be higher.

“Rather than singling out carbohydrate amount as being the key factor, what we need to do is look at what families are doing to achieve targets,” she continued. “We need to look at behaviors—frequent monitoring with correction, multiple doses per day with preprandial insulin, and mealtime structure. We need to consider all macro nutrients.”

Katherine Gallagher, PhD
Katherine Gallagher, PhD

Following the debate, Katherine Gallagher, PhD, and Claire Aarnio-Peterson, PhD, discussed behavioral, psychological, and psychosocial implications of low-carb diets in pediatric type 1 patients.

Dr. Gallagher, a pediatric psychologist at Texas Children’s Hospital and Assistant Professor at Baylor College of Medicine, said there’s limited published data directly examining the psychological and behavioral benefits of carb-restrictive diets in youth with type 1 diabetes. However, these diets may offer mental health benefits as a result of reduced glycemic variability, she said.

“Improved glycemic control may affect mood, energy, and concentration,” Dr. Gallagher said. “Decreased positive mood and increased negative mood ratings are associated with higher blood glucose. We also see greater depression and anxiety symptoms associated with higher A1C. Some research has shown that when A1C decreased, depressive symptoms improved even without targeted mental health treatment.”

Dr. Gallagher also discussed the potential negative behavioral and psychological implications of low-carb diets in youth.

Claire Aarnio-Peterson, PhD
Claire Aarnio-Peterson, PhD

“Higher dietary restraint in type 1 is linked to higher diabetes distress, depressive symptoms, body image and weight concerns, lower self-esteem, and lower self-efficacy,” she said. “In addition, type 1 diabetes is a risk factor for disordered eating, as is dietary restriction. So the combination of the two needs to be considered carefully.”

Dr. Aarnio-Peterson, Assistant Professor and Clinical Psychologist at Cincinnati Children’s Hospital Medical Center, examined the risks of disordered eating in pediatric patients with type 1 diabetes.

“Eating disorder risk factors parallel diabetes management,” she said. “When we think about things like food preoccupation, dietary rules, rigidity about thinking about food—these are all things we see in eating disorders. But for youth with type 1 diabetes, they have to do some of this to obtain good glycemic control. It presents a bit of a conundrum, particularly when trying to treat youth with type 1 and an eating disorder, as the treatment for the eating disorder can be at odds with diabetes management.”

Dr. Aarnio-Peterson said disordered eating behavior is 2.5 times more prevalent in youth with type 1 diabetes.

“Anorexia nervosa has the highest mortality rate of any psychiatric condition,” she said. “When you couple that with the implications of type 1 diabetes, we’re talking about a pretty serious condition.”

Dr. Aarnio-Peterson said youth with type 1 diabetes need to understand the nuance between restraint and dietary restriction. She reviewed data indicating that more restrictive dietary regimens, such as low-carb diets, were more likely to lead to dietary restraint and then to disordered eating behaviors.


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