Prevalence of hypersomatotropism and hyperthyroidism in cats with diabetes mellitus from referral centers in Buenos Aires (2020-2022).

OBJECTIVES: The aim of this study was to estimate the prevalence of hypersomatotropism (HST) and hyperthyroidism in cats with diabetes mellitus (DM) from referral centers in Buenos Aires, Argentina. METHODS: This was a prospective study. Systematic screening of serum insulin-like growth factor 1 (IGF-1) and total thyroxine was performed in all cats diagnosed with DM at referral centers in Buenos Aires between February 2020 and February 2022. RESULTS: In total, 154 diabetic cats were evaluated (99 males and 55 females; median age 12 years [range 3-21]; mean body weight 5 kg [range 2-12]). Altogether, there were 115 (75%) domestic shorthairs and one domestic longhair; the remaining 38 cats were purebred (mainly Siamese, n = 25 [16%]). Twenty (12.9%) cats had IGF-1 concentrations >1000 ng/ml, and three (1.9%) had IGF-1 concentrations between 800 and 1000 ng/ml along with pituitary enlargement on CT, resulting in a 14.9% HST prevalence rate in diabetic cats. Intracranial imaging was performed in all cats with HST; median pituitary dorsoventral height was 5.8 mm (range 3.1-9.5). Fourteen of 23 (61%) cats had phenotypic changes consistent with acromegaly at the time of diagnosis of HST. Four of 154 (2.5%) cats had concurrent hyperthyroidism. CONCLUSIONS AND RELEVANCE: To date, this is the first study outside of Europe to have evaluated the prevalence of HST and hyperthyroidism in cats with DM. In Buenos Aires referral centers, feline HST is the most common concurrent endocrinopathy in cats with DM but with a lower prevalence than has previously been reported. Hyperthyroidism is a rare concurrent endocrinopathy in diabetic cats from referral centers in Buenos Aires.

Cabergoline treatment in cats with diabetes mellitus and hypersomatotropism.

OBJECTIVES: The aim of this study was to evaluate the safety and efficacy of cabergoline to control hypersomatotropism (HST) and diabetes mellitus (DM) in cats. METHODS: This was a prospective cohort study. Twenty-three cats with HST and concurrent DM were enrolled. Cats received a dose of 10 µg/kg cabergoline q48h PO for 6 months. Serum insulin-like growth factor 1 (IGF-1) and fructosamine concentrations, insulin dose and Insulin Resistance Index (IRI) were measured at the time of diagnosis of HST and at the start of cabergoline treatment (t0), and 3 months (t1) and 6 months (t2) during cabergoline treatment. RESULTS: A decrease and normalization of serum IGF-1 concentration was observed in 35% and 26% of cats, respectively. Median IGF-1 (t0: 1350 ng/ml [range 832-1501]; t1: 1284 ng/ml [range 365-1501]; t2: 1240 ng/ml [range 263-1501]; P = 0.016) decreased significantly. Twelve cats underwent diagnostic imaging of the pituitary area. The median pituitary height at t0 of cats that experienced an IGF-1 reduction (n = 5/12) was significantly lower compared with those that did not experience an IGF-1 reduction (n = 7/12) (3.2 mm [range 3.1-3.7] vs 6 mm [range 3.5-9.5]; P = 0.011). Median fructosamine (t0: 628 µmol/l [range 400-963]; t1: 404 µmol/l [range 249-780]; t2: 400 µmol/l [range 260-815]; P <0.0001), insulin dose (t0: 1.3 IU/kg [range 0.5-4.6]; t0: 0.5 IU/kg [range 0-2.3]; t2: 0.4 IU/kg [range 0-2.1]; P <0.0001) and IRI (t0: 800 µmolIU/kgl [range 257-2700]; t1: 300 µmolIU/kgl [range 0-1498]; t2: 250 µmolIU/kgl [range 0-1498]; P <0.0001) decreased significantly during cabergoline treatment. Eight cats achieved diabetic remission between months 1 and 6 of cabergoline treatment (median time to achieve remission: 3 months [range 1-6]). Three cats experienced asymptomatic hypoglycemia. CONCLUSIONS AND RELEVANCE: Cabergoline was effective in normalizing IGF-1 concentration in 26% of cats. Cabergoline improved diabetes control and was associated with remission of DM in 35% of cases. Cabergoline could be a treatment option for cats with HST and DM, especially in those cases with a relatively small pituitary tumor.