Research & Education

Is a Low Carb Diet an Effective Adjunct to Conventional Care for Type 1 Diabetes?

A new paper exploring the efficacy of a very low carbohydrate diet for the management of type 1 diabetes offers insights that could have powerful implications for the way this condition is treated.

Management of type 1 diabetes (T1D) is fraught with risks for hypoglycemia, ketoacidosis, and other potentially fatal complications. The effects of carbohydrate and protein on blood glucose are not always easy to predict, especially when factoring in other issues that affect gluco-regulation, such as physical activity, stress, and quality and quantity of sleep. Matching insulin doses to the amount of carbs and protein in meals is a delicate balancing act that often fails, leading to postprandial blood sugar highs or lows that keep affected individuals on a dangerous rollercoaster daily. Part of this owes to the underrecognized biological fact that the concentration of insulin required to inhibit glucagon release from pancreatic alpha cells is orders of magnitude greater than the concentration that reaches the liver and the rest of the body (muscle cells and adipocytes). So the amount of injected insulin needed to control postprandial hyperglycemia overshoots what the rest of the body needs, often resulting in hypoglycemia.  

Guidelines for blood sugar control for those with T1D are typically more relaxed than for those with type 2, or for the general public. This owes to the potential for dangerous hypoglycemic events when too much insulin is administered: some doctors and professional organizations err on the side of caution, preferring to recommend slightly lower doses of insulin in order to avoid hypoglycemia, with the understanding that this means random blood sugar measurements as well as HbA1c will tend to run higher than may be most desirable.

Unfortunately, those with T1D are not immune to the long-term adverse outcomes from sustained hyperglycemia, and they also suffer negative consequences from long-term insulin therapy, ultimately ending up with symptoms resembling those of type 2 diabetes (T2D) and insulin resistance: weight gain (especially central adiposity), hypertension, arterial calcification, and dyslipidemia. The presence of insulin resistance characteristic of T2D secondary to long-term insulin therapy in an individual with T1D is known as “double diabetes.” (These people often, but not always, have a family history of type 2.) Intensive management of blood glucose with ever-increasing doses of insulin means that HbA1c improves—but it comes at the expense of increased risk for other health complications.

The old paradigm of “carb up and shoot up” (with insulin) has not served type 1 diabetics well. Obviously, the etiology of T1D is completely different from that of T2D, but carbohydrate restriction may nevertheless be an extremely valuable therapeutic tool for those with T1D.

Unlike type 2 diabetics—many of whom are able to discontinue insulin injections after adopting a low carb or ketogenic diet—those with type 1 will always require some amount of exogenous insulin. However, evidence is mounting that a very low carb diet (VLCD) can significantly reduce the amount needed, and the lower the doses of insulin used, the smaller the margin of error, and the less likelihood there may be for hypoglycemic events.

This was reflected in the paper, published in the journal Pediatrics. The research focused on a cohort of children and adults with T1D who use a VLCD to manage blood glucose, guided by the recommendations in the book, Dr. Bernstein’s Diabetes Solution: The Complete Guide to Achieving Normal Blood Sugars, written by a physician with type 1 diabetes. These individuals are part of a Facebook group, TypeOneGrit, in which a commitment to following Dr. Bernstein’s very low carb guidelines to manage T1D is a stipulation for membership.

Among this cohort, mean daily carbohydrate intake (self-reported, or reported by parents for affected children) was 36 ± 15g, and mean HbA1c was 5.67 ±0.66%. Of the participants who reported continuous glucose monitor readings, average blood glucose was 104 ± 16 mg/dL—quite impressive for those with type 1, especially when you take into account the average daily dose of insulin was 0.40 ± 0.19 units/kg/day—also impressive compared to the amounts many others may require.

Overall, these individuals experienced relatively few hypoglycemic episodes, with 69% experiencing 5 or fewer episodes per month, and 18% experiencing 10 or more. Severe episodes were not absent, however: 2% reported hypoglycemia with seizure or coma and 4% required glucagon administration over the previous year. Very low carb diets may reduce the likelihood of these events, but obviously they cannot eliminate them entirely.

Overall, participants reported high levels of satisfaction with their own diabetes control, but fewer were satisfied with their professional medical care:

“Participants reported high levels of overall health and satisfaction with diabetes management but not with their professional diabetes care […] and 27% did not discuss their adherence to a VLCD with their diabetes care providers. Of those who did discuss their diet, only 49% agreed or strongly agreed that their diabetes care providers were supportive. Narrative explanations by participants for not discussing their diet included disagreement on treatment goals and approach, perceived provider disinterest or unfamiliarity with a VLCD, a desire to avoid conflicts with the provider, and (for parents) fear of being accused of child abuse.”

It's an unfortunate state of affairs when individuals achieve impressive blood sugar management with a strategy well-recognized to do just that, yet they feel they have to “hide” it from their healthcare professionals because it’s unconventional. Before the synthesis of synthetic insulin, carbohydrate restriction was the only viable method to provide even a modicum of improved quality of life for people with T1D. That it has fallen out of favor may be due the availability of insulin as well as the longstanding official government guidelines that demonized dietary fat and encouraged liberal consumption of grains and other carbohydrates.

Evidence indicates that dietary carbohydrate restriction may be “the most effective adjunct to pharmacology in type 1.” Again, to be clear, those with type 1 diabetes will always require exogenous insulin. A VLCD may be an adjunct to, not a substitute for, pharmacological management. 

The paper discussed here has several limitations, which the authors are upfront about. One was the demographics of the cohort: 88% were white, non-Hispanic, and 84% (of the adult participants or the parents responding on behalf of children with T1D) had completed college of the equivalent. So this is not a cross-sample of a wider, more diverse population with T1D, and these individuals were all also highly motivated, as they had already been adhering to a strict low carb diet for a mean of 2.2 ± 2.9 years. Nevertheless, you have to start somewhere, and the findings presented are a warning shot across the bow of those who accept HbA1c still in the diabetic range as desirable or “good enough,” knowing full well the long-term complications of chronic hyperglycemia among type 1 diabetics.

Individuals with type 1 diabetes must always closely monitor their blood glucose and should undertake dietary changes only under the supervision of qualified medical professionals. However, the increasing availability of continuous glucose monitors means that they can see in real time how various foods affect them, and they may be in a better position than ever to use that data to guide their dietary choices. A low carb diet should not be dismissed out of hand:

“…we observed measures of glycemic control in the near-normal range, low rates of hypoglycemia and other adverse events, and generally high levels of satisfaction with health and diabetes control. These findings are without precedent among people with T1DM, revealing a novel approach to the prevention of long-term diabetes complications.”

People living with T1D deserve to know that with the right combination of diet and pharmaceuticals, they can achieve truly normal blood sugar.

By Amy Berger, MS, CNS