A novel therapeutic diet in overweight insulin-treated diabetic cats

Introduction

Obesity and associated insulin resistance are commonalities between diabetes mellitus (DM) in cats and human type-2 diabetes. In people with type-2 diabetes, a calorie restricted diet can be an effective strategy for improvement of glycemia and diabetic remission (1). In the management of diabetic cats with concurrent obesity, controlled weight reduction is widely recommended as a means to reduce insulin resistance and improve therapeutic outcomes, including increasing the likelihood of achieving diabetic remission (2). However, published research investigating the effect of restricted energy intake on remission outcomes in overweight diabetic cats has been lacking. Additionally, many commercially available therapeutic diets positioned for cats with DM have not been designed for feeding under the degree of calorie restriction required to achieve substantial weight loss without risking deficient intake of essential nutrients. As such, using a new therapeutic diabetic diet that is suitable for weight reduction, researchers studied the effect of intentional caloric restriction on diabetic remission in overweight insulin-treated diabetic cats in a dual-center, prospective, randomized controlled clinical trial. In the same trial, the researchers also evaluated glycemic control, magnitude of weight loss, indicators of safety of caloric restriction, Diabetes Clinical Score (DCS), and Quality of Life (DIAQol-pet) (3-5).

Study design

Seventy-two client-owned overweight (body condition score ≥ 6/9) diabetic cats treated with protamine zinc insulin (PZI) were included in the 12-week clinical trial. Cats were randomly assigned to either the intervention group (which were fed the study diet under calorie restriction, targeting loss of 2% body weight per week; n=32) or the control group (which were fed the same diet but at a higher calorie allocation to maintain their body weight; n=40).

The study diets, offered in both a dry extruded kibble and a wet format, were designed to be high in protein, low in digestible carbohydrate, low in energy density, and with an increased concentration of essential vitamins and minerals to help ensure adequate nutrient intake despite restricted energy intake. Cats were fed either wet food, kibble, or a combination of these based on cat and owner preferences, with food scales provided to owners to ensure precise food portioning. Figure 1 depicts the study design and parameters that were assessed at each visit throughout the 12-week trial.

Results

Characteristics of included cats 

The median age of the 72 cats in the trial was 11 years; all had previously been neutered, and the majority were male (65%) and domestic shorthair (76%). The median duration of DM for cats included in the trial was 131 days. Between the two groups at baseline, the only significant difference found was glycemic variability, which was greater in the intervention group. There were no significant differences in baseline characteristics, such as body weight, body condition score, muscle condition score, total insulin dose, or duration of DM (3-5).

Weight reduction 

By week 12, cats in the intervention group had lost significantly more weight (average loss of 7.2% of initial body weight) than those in the control group (average loss of 2.7% of initial body weight). Additionally, the body condition scores of the two groups were significantly different at the end of the study period, whilst muscle condition scores did not differ (4).

Diabetic remission 

Significantly more cats in the intervention group (16/32, 50%) had achieved diabetic remission by week 12 than those in the control group (12/40, 30%). (A patient in remission can be defined as an individual previously diagnosed with DM using established criteria, which ceases to receive exogenous insulin therapy and shows no evidence of DM according to the same criteria after 4 weeks (6).) Cats fed under caloric restriction had 2.1 times greater probability of being in remission at 12 weeks compared to those fed for weight maintenance. Factors that were significantly associated with the probability of a cat achieving diabetic remission included a shorter duration of DM and caloric restriction (but not weight change) (3). 

Glycemic control 

Glycemic regulation significantly improved in both groups of cats by week 12 of the trial. For the cats that did not enter into remission, those that underwent calorie restriction were able to have their daily insulin dosage reduced (3).

Safety

Overall, adverse events were few in both groups over the course of the trial, and mostly consisted of non-clinical hypoglycemia (n=4 in the intervention group and n=3 in the control group). One cat in the intervention group had an episode of clinical hypoglycemia. Notably, no cats in either group developed diabetic ketoacidosis or hepatic lipidosis, and there were no hematological abnormalities. On biochemical analyses, serum markers of pancreatic, liver and renal function were stable, with the exception of one cat in the control group that had progression of an existing chronic kidney disease (3).

Quality of life and clinical signs 

Cats in both groups had improved clinical signs of diabetes (based on the DCS, as detailed in Table 1) and improved quality of life. The DCS results were also analyzed excluding evaluation of cat appetite (which could have been affected by the intervention of caloric restriction), and in this context the cats in the intervention group showed greater improvement in diabetic clinical signs (5).

Table 1. Feline Diabetes Clinical Scoring (DCS) system (7).

 

Clinical sign being scored	Severity (compared with prior to onset or diabetes mellitus)	Assigned score
Unintended weight loss over the past 2 months (assessed using body weight records or measurements)	None, intended weight loss or weight gain	0
	Mild (< 5% loss)	1
	Moderate (5-10% toss)	2
	Severe (> 10% loss)	3
Increased drinking and/or urination (assessed by questioning owner)	None	0
	Mild – some increase noted	1
	Moderate – increased filing of water bowl	2
	Severe – constantly seen to drink	3
Increased appetite (assessed by questioning owner)	Normal or decreased appetite	0
	Mild – finishes food eagerly	1
	Moderate – finishes food eagerly and begs for more	2
	Severe – obsessed with food	3
Decreased activity/attitude (assessed by questioning owner)	Normal or increased activity	0
	Mild – slightly less active	1
	Moderate – certainly less active	2
	Severe – mainly lying around	3
	TOTAL SCORE	/12

 

Practical clinical application of the research

Diabetes is a disease that primarily affects mature cats, a life stage at which a large proportion (66.5%) of the population has been reported to have an overweight or obese body condition (8). Although pathologic weight loss is a clinical sign in 60% of cats with uncomplicated DM (2), and this may reduce the degree of adiposity at presentation in historically overweight cats, many diabetic cats will still either have overweight or obesity or be at risk for regaining excessive weight once hyperglycemia has been medically controlled. The findings of this clinical trial serve as compelling evidence for the potential benefits of calorie restriction for weight reduction using a purpose-formulated diet, in combination with medical therapy and close monitoring, on the outcomes of such cats, specifically the achievement of diabetic remission. 

Despite general agreement among veterinary care professionals on the multitude of health benefits of therapeutic weight reduction in overweight pets (with or without concurrent diabetes), weight loss programs in real life settings are both challenging and prone to failure, with only roughly half of cats successfully reaching their target weight (9). Nonetheless, for pets with overweight and obesity, the potential benefit of weight reduction is not limited to cases in which ideal or target weight are attained, as even small degrees of weight loss can positively impact both health and quality of life (10). Indeed, the finding that caloric restriction – and not degree of weight lost – was associated with diabetic remission provides evidence that a substantial weight change is not required for an overweight diabetic cat to benefit from a weight loss program. Early success in the weight loss process may help engage and motivate owners of cats to implement and adhere to a nutrition plan in the longer term, thus realizing the additional benefits of achieving a healthy body condition. Achieving diabetic remission, while not possible in all cases, has been reported to have a positive impact on owner perception of quality of life in diabetic cats (11).

The study findings indicate that restricted calorie intake using a purpose-formulated diet is not only effective in inducing intentional weight loss, but also a safe and well-tolerated intervention in overweight insulin-treated diabetic cats under appropriate veterinary supervision. The weight loss rate of 0.6% body weight per week was similar to that which has been reported in other studies of weight reduction in client-owned overweight cats (12). Additionally, although body composition was not analyzed in the study (e.g., using dual-energy X-ray absorptiometry), the fact that body condition score of cats in the caloric restriction group decreased more than in the control group whilst there was no difference in muscle condition score changes between groups might suggest that weight changes were mainly attributable to loss of body fat, rather than muscle mass. Cats that underwent caloric restriction that did not enter remission required lower insulin doses after the 12-week intervention, and though adverse events were few overall, they included (mostly non-clinical) hypoglycemia in both groups of cats. These findings reinforce the importance of patient monitoring and adjustment of insulin dose when changing the diet (especially to one low in digestible carbohydrates), reducing caloric intake for weight loss, or doing both concurrently, in diabetic cats.

Conclusion

Diabetes and the associated caregiving demands can negatively and sometimes profoundly impact the quality of life of not only the affected cat, but also their owner. Ideally, treatment plans should aim to manage the patient’s glycemia and clinical signs of DM while supporting a good quality of life for both cat and owner. Achieving diabetic remission, while not possible in all cases, has been reported to have a positive impact on owner perception of quality of life in diabetic cats. This clinical trial demonstrated that 50% of overweight diabetic cats managed with insulin therapy and restricted intake of a purpose-formulated diet with veterinary oversight entered remission. However, clinical benefits observed were not limited to remission, as improvements in glycemic control and quality of life were seen in both groups of cats.

 

 

References

1. Jayedi A, Zeraattalab-Motlagh S, Shahinfar H, et al. Effect of calorie restriction in comparison to usual diet or usual care on remission of type 2 diabetes: a systematic review and meta-analysis of randomized controlled trials. Am. J. Clin. Nutr. 2023;117(5):870-882.
2. Taylor S, Cannon M, Church D, et al. iCatCare 2025 consensus guidelines on the diagnosis and management of diabetes mellitus in cats. J. Feline Med. Surg. 2025;27(11):1098612X251399103.
3. Jørgensen FK, Mohanty A, Kieler IN, et al. Effect of 12-week, intentional caloric restriction, using a novel therapeutic diabetic diet suitable for weight reduction, on glycaemic control in overweight cats with diabetes mellitus: an international prospective, randomised clinical trial. Oral research abstract, ECVIM Congress 2025, Maastricht.
4. Bjørnvad CR, Jørgensen FK, Mohanty A, et al. 12-week intentional caloric restriction with a novel purpose formulated feline diabetic weight loss diet is effective and well tolerated in overweight diabetic cats. Oral research abstract, ESVCN Congress 2025, Leipzig.
5. Jørgensen FK, Mohanty A, Kieler IN, et al. Effect of 12-week, intentional caloric restriction, using a novel feline diabetic diet, on clinical signs and quality of life in overweight cats with diabetes mellitus: An international prospective, randomized clinical trial. Poster research abstract, ECVIM Congress 2025, Maastricht.
6. Niessen SJM, Bjornvad C, Church DB, et al. Agreeing Language in Veterinary Endocrinology (ALIVE): Diabetes mellitus – a modified Delphi-method-based system to create consensus disease definitions. Vet. J. 2022;289:105910.
7. Gostelow R, Hazuchova K, Scudder C, et al. Prospective evaluation of a protocol for transitioning porcine lente insulin-treated diabetic cats to human recombinant protamine zinc insulin. J. Feline Med. Surg. 2018;20(2):114-121.
8. Montoya M, Péron F, Hookey T, et al. Overweight and obese body condition in ∼4.9 million dogs and ∼1.3 million cats seen at primary practices across the USA: Prevalences by life stage from early growth to senior. Prev. Vet. Med. 2025;235:106398.
9. O'Connell EM, Williams M, Holden SL, et al. Factors associated with overweight cats successfully completing a diet-based weight loss programme: an observational study. BMC Vet. Res. 2018;14(1):397.
10. German AJ. Weight management in obese pets: the tailoring concept and how it can improve results. Acta Vet. Scand. 2016;58(Suppl 1):57.
11. Rothlin-Zachrisson N, Öhlund M, Röcklinsberg H, et al. Survival, remission, and quality of life in diabetic cats. J. Vet. Intern. Med. 2023;37(1):58-69.
12. Flanagan J, Bissot T, Hours MA, et al. An international multi-centre cohort study of weight loss in overweight cats: Differences in outcome in different geographical locations. PLOS One. 2018;13(7):e0200414.