title: Studying Cat (Felis catus) Diabetes: Beware of the Acromegalic Imposter.
abstract: Naturally occurring diabetes mellitus (DM) is common in domestic cats (Felis catus). It has been proposed as a model for human Type 2 DM given many shared features. Small case studies demonstrate feline DM also occurs as a result of insulin resistance due to a somatotrophinoma. The current study estimates the prevalence of hypersomatotropism or acromegaly in the largest cohort of diabetic cats to date, evaluates clinical presentation and ease of recognition. Diabetic cats were screened for hypersomatotropism using serum total insulin-like growth factor-1 (IGF-1; radioimmunoassay), followed by further evaluation of a subset of cases with suggestive IGF-1 (>1000 ng/ml) through pituitary imaging and/ or histopathology. Clinicians indicated pre-test suspicion for hypersomatotropism. In total 1221 diabetic cats were screened; 319 (26.1%) demonstrated a serum IGF-1>1000 ng/ml (95% confidence interval: 23.6-28.6%). Of these cats a subset of 63 (20%) underwent pituitary imaging and 56/63 (89%) had a pituitary tumour on computed tomography; an additional three on magnetic resonance imaging and one on necropsy. These data suggest a positive predictive value of serum IGF-1 for hypersomatotropism of 95% (95% confidence interval: 90-100%), thus suggesting the overall hypersomatotropism prevalence among UK diabetic cats to be 24.8% (95% confidence interval: 21.2-28.6%). Only 24% of clinicians indicated a strong pre-test suspicion; most hypersomatotropism cats did not display typical phenotypical acromegaly signs. The current data suggest hypersomatotropism screening should be considered when studying diabetic cats and opportunities exist for comparative acromegaly research, especially in light of the many detected communalities with the human disease.
authors.affiliation: Department of Clinical Science and Services, Royal Veterinary College, University of London, London, United Kingdom; The Diabetes Research Group, Institute of Cellular Medicine, University of Newcastle, Newcastle, Tyne and Wear, United Kingdom.
authors.forename: Stijn J M
authors.initials: SJ
authors.lastname: Niessen
authors.affiliation: Department of Clinical Science and Services, Royal Veterinary College, University of London, London, United Kingdom.
authors.forename: Yaiza
authors.initials: Y
authors.lastname: Forcada
authors.affiliation: Department of Clinical Science and Services, Royal Veterinary College, University of London, London, United Kingdom.
authors.forename: Panagiotis
authors.initials: P
authors.lastname: Mantis
authors.affiliation: Department of Clinical Science and Services, Royal Veterinary College, University of London, London, United Kingdom.
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Lamb
authors.affiliation: Department of Pathology and Pathogen Biology, Royal Veterinary College, University of London, London, United Kingdom.
authors.forename: Norelene
authors.initials: N
authors.lastname: Harrington
authors.affiliation: Department of Comparative Biology, Royal Veterinary College, University of London, London, United Kingdom.
authors.forename: Rob
authors.initials: R
authors.lastname: Fowkes
authors.affiliation: Department of Endocrinology, Barts & the Royal London School of Medicine & Dentistry, WHRI, Queen Mary University of London, London, United Kingdom.
authors.forename: Márta
authors.initials: M
authors.lastname: Korbonits
authors.affiliation: Department of Pathology and Pathogen Biology, Royal Veterinary College, University of London, London, United Kingdom.
authors.forename: Ken
authors.initials: K
authors.lastname: Smith
authors.affiliation: Department of Clinical Science and Services, Royal Veterinary College, University of London, London, United Kingdom.
authors.forename: David B
authors.initials: DB
authors.lastname: Church
mesh_terms: D000172:Acromegaly / Q000097:blood / Q000000981:diagnostic imaging / Q000662:veterinary; D000818:Animals; D002371:Cat Diseases / Q000097:blood* / Q000000981:diagnostic imaging*; D002415:Cats; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000000981:diagnostic imaging / Q000662:veterinary; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D011859:Radiography
chemical_list: D007334:Insulin-Like Growth Factor I