Evaluation of insulin-like growth factor-1, total thyroxine, feline pancreas-specific lipase and urinary corticoid-to-creatinine ratio in cats with diabetes mellitus in Switzerland and the Netherlands

Abstract

Objectives The aim of the study was to evaluate circulating insulin-like growth factor-1 (IGF-1), feline pancreas-specific lipase (fPLI) and total thyroxine (TT4) concentrations and urinary corticoid-to-creatinine ratio (UCCR) as indicators for the prevalence of acromegaly, pancreatitis, hyperthyroidism and hypercortisolism in cats with diabetes mellitus. Methods Blood and urine samples were collected from diabetic cats treated in primary care clinics in Switzerland and the Netherlands. Standardised questionnaires and physical examination forms provided clinical information from owners and veterinarians. Laboratory testing included serum biochemistry profile analysis and measurement of circulating fructosamine, IGF-1, fPLI, and TT4 concentrations and UCCR. CT of the pituitary gland was performed using a multidetector computed tomography scanner. Results Blood samples were available from 215 cats and urine samples were collected at home from 117 cats. Age ranged from 2-18 years (median 12 years) and body weight from 2.7-12.3 kg (median 5.5 kg). Sixty-five percent of the cats were castrated male and 35% were female (33% spayed); 82% were domestic shorthair cats. Eighty percent of cats received a porcine insulin zinc suspension, 19.5% insulin glargine and 0.5% a human neutral protamine hagedorn insulin. Thirty-six of 202 (17.8%) cats had IGF-1 concentrations >1000 ng/ml. Serum fPLI, and TT4 concentrations and UCCR were increased in 86/196 (43.9%), 9/201 (4.5%) and 18/117 cats (15.3%), respectively. Prevalence did not differ between countries. Conclusions Hyperthyroidism is rare, whereas increased fPLI concentration, possibly reflecting pancreatitis, is common in diabetic cats. The high UCCR may reflect activation of the hypothalamus-pituitary-adrenal axis, which also occurs in diabetic humans. The percentage of cats with increased IGF-1 was high but lower than reported in recent studies.

Figure 1

Insulin-like growth factor 1 (IGF-1) concentrations (ng/ml) in 202 diabetic cats (All) treated at primary care veterinary clinics in the Netherlands (NL; n = 122) and in Switzerland (CH; n = 80). The bottom and top of a box represent the 25th and 75th percentiles, the line inside the box represents the median, the lines at the whiskers represent the 2.5th and 97.5th percentiles and the dots represent outliers

Figure 2

Feline pancreas-specific lipase immunoreactivity (fPLI) concentrations (µg/l) in 196 diabetic cats (All) treated at primary care veterinary clinics in the Netherlands (NL; n = 118) and in Switzerland (CH; n = 78). Key to box plots as for Figure 1

Figure 3

Total thyroxine (TT4) concentration (nmol/l) in 201 diabetic cats (All) treated at primary veterinary care clinics in the Netherlands (NL; n = 118) and in Switzerland (CH; n = 83). Key to box plots as for Figure 1

Figure 4

Urinary corticoid-to-creatinine ratio (UCCR) in 118 diabetic cats (All) treated at primary veterinary care clinics in the Netherlands (NL; n = 106) and in Switzerland (CH; n = 12). Key to box plots as for Figure 1