Weight Loss Via Diet in Type 1 Diabetes Is Feasible, Safe

Miriam E. Tucker

November 18, 2022

A variety of dietary approaches can help people with type 1 diabetes lose weight without increasing the risk for hypoglycemia or adversely affecting glycemic control, new pilot study data suggest.

Results from the first 3 months of the randomized Advancing Care for Type 1 Diabetes and Obesity Network (ACT1ON) study were published online in Diabetes, Obesity & Metabolism by Daria Igudesman, PhD, a postdoctoral fellow at the AdventHealth Translational Research Institute, Orlando, Florida, and colleagues.

Although overweight and obesity are generally associated with type 2 diabetes, today more than two thirds of adults with type 1 diabetes also have overweight or obesity. This proportion has more than doubled over the past three decades, with obesity among those with type 1 diabetes in particular escalating from 3.4% in 1986-1988 to 36.8% in 2018. And, like those with type 2 diabetes, people with type 1 diabetes are at considerably greater risk for cardiovascular disease than those without diabetes.

"It is important to manage weight in people with type 1 diabetes for many of the same reasons it's important in type 2 diabetes. The excess weight can counter the cardiovascular benefits of intensive insulin therapy," Igudesman told Medscape Medical News.

Nonetheless, very little research has been conducted on dietary approaches for weight loss in type 1 diabetes. Any such study must incorporate the special considerations in type 1 diabetes, including the need to avoid hypoglycemia, hyperglycemia, and diabetic ketoacidosis while continuing to use exogenous insulin therapy. Other challenges include the need to ingest carbohydrates when hypoglycemia does occur and the fear of hypoglycemia as a barrier to exercise.

In the ACT1ON pilot, three different types of diets — a hypocaloric low-carbohydrate diet, a hypocaloric Look AHEAD (moderate low-fat) diet, and a noncalorically restricted healthy Mediterranean diet — all promoted weight loss at 3 months without adversely affecting A1c or increasing hypoglycemia risk.

Igudesman suggests that clinicians who see patients with type 1 diabetes who have overweight or obesity should "certainly take a few moments to ask patients whether and how they would like to discuss their weight because of course it's a very sensitive topic for a lot of people. If they're amenable to that conversation, then referral to a dietician or a diabetes care and education specialist [formerly known as a diabetes educator] can help to establish a personalized strategy."  

3 Diets All Promoted Weight Loss, None Raised A1c or Hypoglycemia

The pilot study was designed to take place over 9 months, with participants randomized to sequences of each of the three diets for 3 months each. The protocol was planned to allow for re-randomization at months 3 and 6, but COVID-19 restrictions necessitated a change after the first 3 months, and thus, those are the only data in the current report. Full results will be published at a later date, Igudesman said.

Participants were aged 19-30 years, had type 1 diabetes for at least a year, and had a body mass index of 27-39.9 kg/m2. All were monitored with blinded continuous glucose monitoring (CGM) while also using their usual personal methods of monitoring and insulin adjustments.

At 3 months, all three diet groups lost weight: 2.4 kg (5 lb) with the low-carbohydrate diet, 1.3 kg with the low-fat Look AHEAD diet, and 2.4 kg with the Mediterranean diet. The overall adjusted weight change was a drop of 2.7 kg (P < .0001 from baseline), with no significant differences among the three groups (P = .34). Overall, women lost significantly less weight than men (P = .02).

A1c dropped significantly with the low-fat Look AHEAD diet (by 0.65 percentage points, P = .027) but not the other diets. After adjustment for several factors including baseline A1c, gender, race, and ethnicity, A1c decreased by 0.91 percentage points (P = .005) overall and didn't differ across diet groups (P = .09). The percent of time spent in glucose range of 70-180 mg/dL was consistent with the A1c in that it increased numerically but didn't reach statistical significance (P = .09) nor did it differ across diet groups (P = .46).

The percentage of time spent with glucose levels below 70 mg/dL didn't increase overall from baseline to 3 months (P = .25) or in any of the diet groups. However, absolute percent time below range was higher in the low-carbohydrate diet group (9.1%) than with the low-fat Look AHEAD diet (3.1%) or the Mediterranean (3.3%) diet (P = .04). The percentage of time below a glucose level of 54 mg/dL was just 0.82% overall and didn't change significantly from baseline in any of the groups.

"Weight loss and glycemic management are not inexorably at odds with one another in the clinical management of [type 1 diabetes], and...a variety of diet approaches — including those that do not require explicit calorie restriction — can be effective to serve these equally important goals," Igudesman and colleagues write.

Next steps will likely include another non-interrupted pilot study, followed by a fully powered randomized clinical trial that will include greater standardization of aspects such as insulin dosing and activity, with the aim of determining predictors of weight loss in people with type 1 diabetes. Ultimately, the goal is to develop weight management guidelines that allow for personalized approaches.

Igudesman said: "We're planning to continue this work long-term because there's a lot more evidence we need...for us to deliver on those guidelines. This is really a long-term endeavor."

The research was funded by the National Institute of Diabetes and Digestive and Kidney Diseases of the National Institutes of Health. Igudesman was supported by the NIH Global Cardiometabolic Disease training grant awarded to the Department of Nutrition at the University of North Carolina at Chapel Hill.

Diabetes Obes Metab. Published online October 31, 2022. Abstract

Miriam E. Tucker is a freelance journalist based in the Washington, DC, area. She is a regular contributor to Medscape, with other work appearing in The Washington Post, NPR's Shots blog, and Diabetes Forecast magazine. She is on Twitter: @MiriamETucker.

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