Glycemic control through weight loss: Evidence and clinic implementation

John Flanagan, PhD, and his research team recently completed a prospective, randomized trial of a purpose-formulated diabetic diet (Glycoadvanced; Royal Canin) in overweight, insulin-treated cats. The clinical study was a research collaboration between Royal Canin, and 2 prestigious European veterinary schools, Copenhagen University and the Royal Veterinary College, London. The study assessed whether feeding the diet with intentional caloric restriction improved rates of diabetic remission and glycemic control compared with feeding the diet for weight maintenance. This Q&A is drawn from an interview with dvm360 at the 2026 Western Veterinary Conference (WVC) in Las Vegas, Nevada. Below are some answers, key trial methods, and outcomes from a study provided by Royal Canin.

Please introduce yourself and your role in this research.

Flanagan: My name is John Flanagan. I am a research scientist at Royal Canin, and I have been with the company for more than 10 years. My background is in food technology. I have a PhD in food technology from the University of Limerick, and I have held research positions in companies in France and Spain, [as well as] a postdoctoral position in New Zealand. I'm at WVC to talk about a new diabetic diet that Royal Canin is launching, Glycoadvanced. I was involved in the study design from the start, and I'm very proud to see it come to market over the [past] 3 months.

What question did the trial seek to answer?

Flanagan: The study involved overweight diabetic cats. We wanted to see whether putting them on the new Glycoadvanced diet could help more cats achieve diabetic remission. The diet we developed focuses on the needs of overweight diabetic cats.

How is Glycoadvanced formulated to meet those needs?

Flanagan: It is high in protein, low in digestible carbohydrates, reduced in energy, and has an increased nutrient-to-calorie ratio to meet the needs of cats during weight reduction. For diabetic cats, it is generally recommended to use a diet low in carbohydrates—specifically, low in digestible carbohydrates—because cats cannot manage large glucose loads after a meal. Weight-reduction diets on the market are typically high in total dietary fiber, reduced in energy, low in fat, and have an increased nutrient-to-calorie ratio, so cats get the nutrients they need while under calorie restriction. To show the benefits of weight reduction in overweight diabetic cats, we had to meet the needs of both groups: diabetic cats that require low digestible carbohydrates and high protein, and overweight cats that require lower energy density and an increased nutrient-to-calorie ratio.

(Trial documentation confirms the diet was purpose-formulated to support glycemic regulation while enabling safe caloric restriction with an increased nutrient-to-calorie ratio.)

Who was enrolled, and what was the study design?

Flanagan: For the study, we recruited 72 overweight diabetic cats that had previously been on insulin. We divided them into 2 groups. One group was fed Glycoadvanced at levels intended to maintain body weight, and the second group was fed Glycoadvanced with caloric restriction to promote weight loss.

(Per protocol: A dual-center, prospective, randomized controlled trial of client-owned, insulin-treated cats with a body condition score (BCS) ≥ 6/9 [n = 72], median age of 11 years, and median weight of 13.2 lb. Study sites included the University of Copenhagen and the Royal Veterinary College.)

How exactly was caloric restriction implemented and monitored?

Flanagan: There was a 1-week food adaptation where both groups were fed for maintenance of body weight, followed by a 12-week intervention period. The control group was fed for maintenance of initial body weight. The intervention group was fed with restricted caloric allocation with a target of 2% weekly weight reduction. Calorie allocation was revised weekly based on at-home weight checks using electronic cat scales provided to all owners. We also provided feeding stations for households with multiple cats to prevent cats from eating each other’s food.

(Protocol required weekly home weighings and clinic visits at weeks 4, 8, and 12; caloric allocation in the restriction group averaged approximately 60% of maintenance energy requirements.)

What safety precautions were in place during intentional weight loss?

Flanagan: We were very conscious of safety when running a weight-loss program in overweight diabetic cats because this had not been done before. We consulted widely with experts experienced in weight-reduction programs for cats. For otherwise healthy overweight or obese cats, we typically recommend weight loss of about 0.5% to 2% per week, and we thought this was a reasonable target in overweight diabetic cats, as well. We put several safety measures in place to closely monitor the cats and to watch for any signs of problems during weight loss. We monitored clinical chemistry and hematological parameters throughout the trial and were pleased to find no signs of serious adverse events. The issues we saw were mostly minor, nonclinical hypoglycemia. There were no signs of pancreatitis, hepatic lipidosis, or ketoacidosis. Renal and liver functions remained normal for most cats, with the exception of 1 cat in the control group whose [chronic kidney disease] worsened slightly over 12 weeks.

(Study safety findings: No cats developed diabetic ketoacidosis or hepatic lipidosis; laboratory monitoring and clinical exams were performed at scheduled visits.)

How was owner adherence supported?

Flanagan: We were fortunate that the pet owners were highly engaged, which made [adherence] much easier. We provided owners with tools to help manage the cats, including scales so they could weigh food portions daily and scales to weigh their cats. We also taught owners how to perform blood glucose curves, and for those who were not able to do a full curve, we asked for spot glucose measurements. All of these measures helped owners participate in the study, and we achieved excellent [adherence].

(Protocol limited treats to ≤ 10% of daily energy and required blood glucose curves at home at weeks 4, 8, and 12 or spot checks when a full curve was not feasible.)

What were the primary outcomes?

Flanagan: By week 12, 50% of cats fed for caloric restriction went into remission compared with 30% of cats fed for weight maintenance. Cats fed for caloric restriction were 2.1 times more likely to achieve diabetic remission than cats fed for weight maintenance [P < .05]. Even for cats that did not achieve remission, those fed for caloric restriction achieved greater glycemic control and a reduced insulin dose compared with cats fed for weight maintenance. Insulin dose decreased by 36% in cats that underwent caloric restriction, and glycemic variability decreased by 45% in cats that underwent caloric restriction.

(Additional trial metrics: Mean weight loss at 12 weeks was approximately 7.2% in the caloric restriction group vs approximately 2.7% in the maintenance group [P < .001]. Most remissions occurred in the first 6 weeks; remission was more closely associated with the degree of caloric restriction than with the rate of weight loss.)

Any clinical takeaways for practitioners?

Flanagan: Intentional caloric restriction with Royal Canin Glycoadvanced improves the likelihood of diabetic remission, improves regulation of blood glucose levels, and promotes healthy weight when fed as part of a veterinary diabetic management program in combination with medical therapy. Feeding a standard diet under similar caloric restriction could result in essential nutrient deficiencies. Glycoadvanced is purpose-formulated with an increased nutrient-to-calorie ratio for safe use during caloric restriction in diabetic cats.

(Clinical relevance: Caloric allocation averaged approximately 60% of maintenance in the restriction arm and was well tolerated. Quality-of-life scores improved in both groups; remission rates did not differ by wet vs dry feeding mode.)

Were there any limitations or unanswered questions you encountered?

Flanagan: We were very conscious of safety and monitored closely. The study was 12 weeks long, and most remissions occurred within 6 weeks, but longer follow-up will be informative to know the durability of remission. Also, because the study used a purpose-formulated diet, the benefits seen with caloric restriction may not generalize to standard maintenance diets if used without the increased nutrient density.

(The trial was dual-centered and randomized, but subsequent peer-reviewed publication will clarify methods and secondary analyses; the sponsor notes the manuscript was submitted for publication.)