The short answer
Diabetes mellitus in cats is a common endocrine disease; most cases resemble human type 2 diabetes, and a smaller share are driven by excess growth hormone. The 2025 iCatCare consensus guidelines describe diagnosis under the ALIVE criteria, which highlight the need to avoid an incorrect diagnosis due to stress hyperglycaemia. Treatment is either insulin or, for clinically well cats, an oral sodium-glucose cotransporter-2 inhibitor (SGLT2i), combined with diet and a monitoring plan the caregiver can sustain. Remission is reported in roughly 11% to over 60% of insulin-treated cats across studies, and it is more likely with early diagnosis, rapid glycaemic control and weight loss in obese cats.
Key takeaways
- The iCatCare panel states that feline diabetes is assumed to resemble human type 2 diabetes in 75% to 80% of cases and to be secondary to hypersomatotropism in 20% to 25% [1].
- The 2025 guidelines note that stress hyperglycaemia "can be of any magnitude," and that the diagnostic criteria highlight the need to avoid an incorrect diagnosis due to stress hyperglycaemia [1].
- The iCatCare panel found little published evidence that any one insulin formulation is better than another for feline diabetes [1].
- Field studies cited by iCatCare found velagliflozin and bexagliflozin effective in about 80% to 90% of cases. The panel names euglycaemic diabetic ketoacidosis (eDKA) as the most serious adverse event [1].
- Remission is defined as "zero requirement for exogenous insulin for at least 4 weeks, with no clinical signs of DM," according to the iCatCare guidelines [1].
- The iCatCare guidelines report that effective early weight loss is associated with a 15-fold increase in remission odds [1].
Doses on this pageEvery dose below is quoted from the cited source. Verify against the current label/formulary and the patient's full clinical picture.
Definition, risk factors and presentation
The iCatCare guidelines describe diabetes mellitus as a syndrome of hyperglycaemia caused by defective insulin secretion, insulin sensitivity, or both [1]. In the type 2 form, the panel describes partial beta cell dysfunction, beta cell loss and insulin resistance. Glucotoxicity then causes further beta cell injury in a self-reinforcing cycle [1]. The Merck Veterinary Manual identifies amyloid deposition in the islets as the most common pancreatic lesion in many diabetic cats [3].
The 2015 ISFM guidelines list these risk factors [2]:
- obesity, which makes cats up to four times more likely to develop diabetes
- age over 7 years
- Burmese breed, in studies from Australia, New Zealand and Europe
- physical inactivity
- male sex and neutering
- glucocorticoid or progestagen treatment
Merck adds that cats over 4 kg seem more commonly affected [3]. iCatCare cites one study in which high-dosage prednisolone (at least 1.9 mg/kg q24h for more than 3 weeks) led to diabetes in 9.7% of cats, mostly within the first 3 months [1].
Classic signs listed by iCatCare are polyuria and polydipsia, weight loss despite polyphagia, and lethargy. Prolonged hyperglycaemia can cause diabetic neuropathy with a plantigrade stance [1]. The sources differ on appetite. Merck states that up to 50% of diabetic cats have a decreased appetite [3]. The 2025 iCatCare panel says diabetic cats are typically not hyporexic and that reduced appetite should prompt a search for comorbidity or ketoacidosis [1].
Diagnosis and testing pitfalls
The iCatCare guidelines adopt the diagnostic criteria of the Agreeing Language in Veterinary Endocrinology (ALIVE) project. The panel stresses avoiding misdiagnosis from stress hyperglycaemia [1]. Where diabetes and stress hyperglycaemia cannot be separated, the panel lists home blood glucose, continuous glucose monitoring (CGM) and dipstick testing of home-collected urine as useful. It suggests periodic reevaluation if doubt persists [1].
The iCatCare guidelines describe two glycated protein tests, each with its own pitfalls [1]:
- Serum fructosamine reflects roughly the previous 7 to 10 days of glucose. It can be normal in early diabetes. Hyperthyroidism and protein-losing enteropathies falsely lower it, and hypothyroidism falsely raises it. Haemolysis shifts it in an unpredictable direction.
- Haemoglobin A1c reflects 68 to 77 days of glycaemia. Anaemia falsely raises it, but haemolysis and protein turnover do not affect it.
The 2015 ISFM guidelines recommend these initial tests: history, physical examination, biochemistry and complete urinalysis. Ideally the workup would also include a complete blood count, fructosamine and serum thyroxine in older cats [2]. The renal threshold for glucose is given as about 15 mmol/l (270 mg/dl) by iCatCare [1] and approximately 280 mg/dL by Merck [3].
Classification and underlying causes
None of the sources describes a formal staging system for feline diabetes. The iCatCare panel says prediabetes probably occurs in cats, but a lack of evidence, including validated glucose tolerance tests, has so far prevented identifying it [1]. The 2025 guidelines instead describe a practical initial assessment. A newly diagnosed cat is first assessed for complicating factors. Inappetence, dull demeanour, severe lethargy or dehydration point toward urgent treatment, often under a ketoacidosis protocol [1].
Hypersomatotropism (HST) is the preferred term over acromegaly. The panel describes it as the leading cause of clinically relevant insulin-resistant diabetes in cats, affecting an estimated 1 in 3 to 1 in 5 diabetic cats [1]. About 75% of cats with HST look like ordinary diabetic cats on physical examination. For that reason the panel advises discussing screening with caregivers of all diabetic cats [1]. Serum IGF-1 is the screening test. A validated assay showed a minimum 95% positive predictive value at 1000 ng/ml, and 700 to 1000 ng/ml is treated as a grey zone [1]. Insulin deficiency lowers IGF-1, so the panel considers results taken after 6 to 8 weeks of treatment more reliable [1]. Hypercortisolism is less common and leads to overt diabetes in about 80% of affected cats [1].
Insulin therapy and diet
iCatCare notes that two veterinary insulin formulations are approved for use in cats, compared with more than 10 human formulations, some of which are routinely used in cats [1]. The panel classes porcine lente, NPH, PZI, glargine U100 and degludec as intermediate-acting and generally recommends twice-daily use [1]. It describes glargine U300 as the closest to a once-daily basal insulin in cats, although its duration is often too short for once-daily dosing [1]. Studies comparing PZI with glargine U100 reported similar remission rates [1]. Merck gives a starting dosage for protamine zinc insulin (PZI) of 0.25 U/kg (1 U/cat), SC, every 12 hours, and for insulin glargine of 0.25 to 0.5 U/kg (1 to 2 U/cat), SC, every 12 hours. It advises basing doses on estimated ideal body weight [3].
For twice-daily intermediate-acting insulin, the iCatCare panel sets a glucose target. The low point should be normal, 4.5 to 5.5 mmol (80 to 100 mg/dl), and the peak 14 to 19 mmol/l (250 to 350 mg/dl) [1]. The panel cautions that evidence linking any glycaemic target to outcomes is lacking, and it advises against micromanagement [1]. It finds no reason to withhold insulin when a cat skips a meal, provided the cat is otherwise well and the inappetence is not ongoing [1].
On diet, iCatCare recommends a low-carbohydrate food, defined as "<25% dry matter, <15% metabolisable energy, <5 g/100 kcal" [1]. The panel adds that a particular diet should not be pursued at the cost of food intake or caregiver finances [1]. For overweight cats it suggests a target body condition score of 5/9 and weight loss of around 0.5% to 1% per week at most [1].
SGLT2 inhibitor therapy
SGLT2 inhibitors block glucose reabsorption in the proximal renal tubule and lower blood glucose independently of insulin secretion [1]. Merck lists the dosages as velagliflozin 1 mg/kg, PO, every 24 hours, and bexagliflozin 15 mg/cat (in cats weighing at least 3 kg), PO, every 24 hours [3]. iCatCare cites a comparison with porcine lente insulin, in both insulin-naive and previously insulin-treated cats, that concluded velagliflozin was non-inferior [1].
The iCatCare panel considers these drugs suitable for clinically well ("happy") diabetic cats without conditions that predispose to eDKA, such as dehydration, poor body condition, gastrointestinal signs, clinical pancreatitis or ketosis [1]. eDKA affected 1 in 15 newly diagnosed cats and 1 in 10 previously insulin-treated cats in the field studies, the panel reported [1]. Merck states that SGLT2 inhibitors are contraindicated in cats previously treated with insulin [3]. The 2025 iCatCare guideline, by contrast, reports eDKA rates in previously insulin-treated cats and cites a trial that included them [1]. The guideline recommends clinic checks at the end of weeks 1, 2 and 4. It calls ketone testing "mandatory" whenever a treated cat becomes unwell [1]. Diarrhoea and vomiting were the most common adverse events, and clinical hypoglycaemia was not reported in the field studies [1]. Urine glucose is not useful for monitoring these cats [1].
Monitoring
The iCatCare panel prioritises clinical signs. It suggests the ALIVE Diabetic Clinical Score as a practical method; the score rates weight loss, polyuria and polydipsia, appetite and activity for a total of 0 to 12 [1]. Fructosamine is best read as a trend. The panel suggests a baseline and a repeat 2 to 3 weeks after a treatment change [1]. A value within the reference interval in an insulin-treated cat should prompt assessment for remission or overdosing [1].
According to iCatCare, the FreeStyle Libre is the most commonly used CGM device in cats. Its accuracy in diabetic cats is considered acceptable but appears lower in the hypoglycaemic range [1]. The device can be worn for up to 14 days, but the most common complication reported in cats was reduced sensor lifespan, at 5.5 to 10 days [1]. For home blood glucose curves, the panel notes that human glucose meters typically read lower in cats than veterinary meters [1].
Remission, prognosis and client communication
The iCatCare panel states that the wide range of reported remission rates, 11% to over 60%, likely reflects the heterogeneity of the disease [1]. Remission lasts a median of 120 to 150 days, between 13% and 40% of cats relapse, and a second remission appears less likely [1]. The panel associates remission with shorter disease duration, milder hyperglycaemia at diagnosis, and rapid good control. Stopping corticosteroids also improves the odds, while neuropathy lowers them [1]. Remission under SGLT2 inhibitors is not well researched. The only way to identify it is to stop the drug and monitor glucose [1].
On prognosis, the 2015 ISFM guidelines cite median survival times of 13 to 29 months, longer in better-stabilised cats [2]. iCatCare reports that cats with ketoacidosis have mortality of 26% to 41% and recurrence of 18% to 42% [1]. Merck states that up to 25% of diabetic patients are euthanized on the day of diagnosis, often for reasons education could address [3]. The iCatCare panel recommends discussing hypoglycaemia signs with caregivers. Those signs are most commonly neurological: ataxia, trembling, lethargy, vomiting and seizures. The panel also suggests keeping glucose syrup or honey at home [1].
