Experts came together virtually at the American Diabetes Association (ADA) 80th scientific sessions on Sunday afternoon to debate the potential pros and cons of utilizing low-carbohydrate diets among youth with type 1 diabetes. Dr. Belinda Lennerz, MD, PhD of the Boston Children’s Hospital discussed the pros of utilizing low-carb eating (defined, in this case, as <20-50g per day or <10% of the daily caloric intake) in this patient population, while Dr. Carmel Smart, Rd, PhD of the John Hunter Children’s Hospital argued about the potential cons. Each presenter made their case and were also allowed time to rebut. Here is the summary of the experts’ arguments.
Potential Pros of a Low-Carb Approach
Dr. Lennerz started by providing a historical overview of low-carb diets among patients with type 1 diabetes, noting that even after insulin became available, carb intake initially stayed low for patients. In fact, it was only once fat was implicated in the development of cardiovascular disease (CVD), that the recommendations to increase carbohydrate intake were made, to replace the calories lost by omitting fat. She also pointed out that currently there is no one-size-fits all recommendation for carbohydrate intake, and that guidelines state it should be individualized.
The presenter addressed the differences in carbohydrate intake levels in the “low-carb spectrum” and was also careful to quickly touch upon the important distinction of ketosis vs. diabetic ketoacidosis (DKA). Ketones present at low levels due to eating low-carb are very different than the level of ketones seen in acidosis. Unfortunately, these terms that are often conflated, even by some clinicians, leading many to erroneously believe that low-carb diets are inherently unsafe for people with diabetes.
Dr. Lennerz went on to explain that many people with type 1 diabetes, including children, are successfully utilizing a low-carb dietary approach to better manage their diabetes.
“Why might a low-carb diet appeal to someone with type 1 diabetes?” she asked, going on to talk about the issue of glycemic variability that many experience, noting that post-meal blood glucose levels are large component of overall glycemic control and variability. Furthermore, glycemic variability is an independent risk factor for heart disease. She presented a graph two patients with varying levels of glycemic management and noted that even the more tightly controlled patients still experienced frequent postprandial blood glucose excursions that were above their target level. More importantly, these blood glucose excursions, she argued, are largely caused by carbohydrate, due to a mismatch in insulin action and timing against carb digestion.
Moreover, she noted that today, children with type 1 diabetes have higher levels of overweight, obesity, and metabolic syndrome, potentially due to a higher carbohydrate diet and corresponding insulin use, or may be in part due to using too much insulin and consuming additional carbohydrates to treat low blood glucose levels.
Next, Dr. Lennerz outlined how low-carb eating could effect positive change for patients and contrasted the potential benefits again commonly-cited concerns of “inadequate carbohydrate intake”. In short, low-carb eating could help patients minimize blood glucose excursions, which could offer numerous benefits, including:
- Lower risk of hypoglycemia
- Higher quality of life
- Cognitive benefits
- Better growth and development
- Potential reduction in CVD risk (lower triglycerides, higher HDL cholesterol)
In contrast, she noted some common concerns, including:
- Lower glycogen stores and potentially more hypoglycemia
- Lower quality of life due to “restrictiveness”
- Sufficient fuel (glucose) for the brain
- Potential for nutritional deficiency (that could negatively affect growth and development)
- Potential for increased cardiovascular disease risk (higher LDL cholesterol levels)
Importantly, Dr. Lennerz noted that the available scientific literature to “substantiate or refute these concerns” was scarce, essentially meaning that the commonly-discussed concerns are largely hypothetical.
Next, Dr. Lennerz dove into data from various research studies on low-carb diets in patients with diabetes, first noting positive benefits among patients with type 2 diabetes (improved A1c, insulin sensitivity, etc.), as well as highlighting several case studies that pointed to the safety of the approach in children, young adults, and adults with type 1 diabetes.
Notably, a study published in 2018 showed “unprecedented results” for adults and children in diabetes. These patients achieved clinically-normal A1c levels with little glycemic variability and a very low rate of diabetes-related hospitalizations. Contrasting the glycemic profiles of these patients with the average levels of glycemic management in the US provided a striking visual.
Dr. Lennerz also discussed the relevance of the patient lipid profile in CVD risk, stating that although some studies show elevations in LDL cholesterol levels on a low-carb diet, research shows that A1c and total daily insulin dose, among other factors, are much more important in qualifying CVD risk than LDL levels.
In summary, she stated,
“Generally, very low-carb diets are not recommended for type 1 diabetes in the guidelines because of potential hypothetical risks, though we don’t have any data to substantiate those risks. They are highly popular among patients, they are physiologically-plausible, and could be beneficial. Medical supervision is needed… to achieve nutritional sufficiency, appropriate insulin dosage adjustments, and ketone monitoring.”
Potential Cons of a Low-Carb approach
Dr. Smart began her presentation by stating that her goal was to bring awareness to families and clinicians about the “potential pitfalls” of low-carbohydrate diets and to “provide a voice” to those who follow a higher-carb eating plan but also achieve “optimal” results.
“Is a low-carbohydrate eating pattern necessary to reach tightly-controlled glucose in children and what risks must be considered?” asked Dr. Smart. She went on to discuss that “not all carbohydrates are created equal”, underscoring the nutritional value of certain food with higher carb counts, in contrast to packaged and processed carbohydrates that are not generally recommended. The message that “you can eat anything you’d like and dose insulin for it” is an incorrect one, she stated, explaining that scientific evidence shows that different types of carbohydrates can have a different impact on glycemic profile.
She also noted that many children with whom she has worked are “fussy” eaters, underscoring the importance of offering a wide variety of options. Dr. Carmel went on to explain that advocating a “one size fits all” eating plan isn’t a good idea, because energy needs in children are based on growth and activity.
Similar to Dr. Lennerz, Dr. Carmel acknowledged that there is a lack of scientific data on low-carbohydrate eating in pediatric patients with type 1 diabetes. She went on to outline the following potential concerns about low-carb eating in children:
- Higher fat intake
- Too much focus on the specific amount of carb intake, instead of acknowledgement that “not all carbs are created equal”
- Delayed blood glucose rise from fat and protein intake that impacts insulin requirements
- Oversimplified messaging that may erroneously suggest that glycemic management on a low-carb diet requires little effort
- Potential for negative effects on cognition
- Potential for low adherence to a prescribed eating plan
- Potential for poor growth and development
- Inadequate nutrient intake
- Risk of DKA (including euglycemic DKA)
- Lack of “social normalcy”
Dr. Smart also pointed out that there have been some studies in adults with type 1 diabetes, where lowering the carbohydrate intake did not result in improved glycemia. However, the studies she cited involved a higher amount of carbohydrates, outside the established definition of “low-carb” in this discussion. She also went on to suggest the weight loss seen by some adults with type 1 diabetes on low carb diets may be a concern for growing children.
Dr. Smart went on to address several considerations on the only low-carb study in children (see above), warning that the most appropriate interpretations of the positive outcomes are limited due to potential selection and reporter bias. The presenter noted once more that there is a lack of evidence for or against the use of low-carb diets in youth and highlighted that many “national food agencies” recommend a “moderate carb” intake.
Finally, Dr. Smart presented her final argument, stating,
“There is an assumption that you cannot achieve target glycemia on a usual carb diet… In our clinic, over 83% of patients achieve target glycemia… It is indeed possible to match insulin, if given at the right time, and appropriately matched to the food profile to ensure that glycemic rises are not excessive.”
She went on to present some one-day blood glucose data from some of her patients, to demonstrate that insulin dosing could be optimized for higher-carbohydrate eating, and cited additional data on the A1c levels in her patients (6.4% +/- 0.9%), explaining that these patients eat plenty of carbohydrates (e.g., 170 g+ per day).
Dr. Smart explained that other behaviors, such as checking blood glucose levels frequently, and a deep understanding on how different foods impact blood glucose levels and the corresponding insulin dosing strategy, were much more important to achieving better glycemic control than the grams of carbohydrates consumed.
The following notable quotes by each respective researcher in the rebuttal portion of the debate are presented below.
“Healthy foods are important… I think nutritional sufficiency can be achieved with a very low-carb diet, and I think a hypocaloric status is often related maybe to a “fat fear”, where people are hesitant to eat adequate amounts of fat to compensate for the lost calories from carbohydrate…
I think we have to get away from the term “restriction” and see this rather as offering alternative food choices, and I think like any dietary approach in children, this has to be a family affair… If this is a choice a family is making, I do see a role for low-carb diets and very low-carb diets in a setting of a personal approach…
Given the complexity of diabetes care, I don’t think it’s easy to ask a family to also think of the glycemic index, protein, fat, fiber, and so forth, when they make their diabetes decisions… Some patients may choose to reduce carbohydrate intake instead of making these complex assessments.”
“It is restricting the amount of carbohydrate, because these are commonly-eaten foods. Breads, cereals, pasta are commonly eaten foods across all cultures… You are asking families to restrict the foods that they eat.
It would be fair to say that families that are of high socioeconomic status have time and energy to do this…. If you then try to translate it across the board, other families then become guilty and think that they can’t do this.
It is extremely difficult to get energy intake [on ~30g/day carbohydrate intake] in active young people. I would be very interested to see some published dietary data on what these young people are eating, particularly as, fat and protein occur together in foods, so if you’re saying protein is satiating, you’d have to be eating very large amounts of fat… [Some] people eat… butter by itself… I don’t think most scientists and most clinicians would view that as healthy thing to do…”
Should children with type 1 diabetes and their families consider a low-carb diet?
Currently, there is substantial scientific evidence on the health benefits of this approach for people with diabetes; in fact, numerous studies have shown significant benefits. However, more research is required to validate this in the pediatric population. Meanwhile, blood glucose management among children and adolescents is far from optimal, despite continuing treatment and technology advances. Concerns raised about low-carb eating in youth, while important, are largely hypothetical, further highlighting that more research is needed across the board on this topic.
Dr. Michael J Haller, MD, Professor and Chief of Pediatric Endocrinology at the University of Florida, who chaired the debate, concluded:
“Clearly not an issue where we’re going to come to an answer today. The research still needs to be done… Importantly, in personalized medicine, we are seeing that there are different ways to manage our patients. They can all achieve success. That’s important to understand.”
What are your thoughts on the subject?
Stay tuned for more from the ADA 80th scientific sessions!