Long-term field study of lispro and neutral protamine Hagedorn insulins treatment in dogs with diabetes mellitus

Background: The long-term clinical and biofhemical effects of basal-bolus insulin treatment with lispro and NPH in dogs with diabetes mellitus are undocumented. Objectives: To perform a prospective pilot field study of the long-term effects of lispro and NPH on clinical signs and serum fructosamine concentrations (SFC) in dogs with diabetes mellitus. Methods: Twelve dogs received combined lispro and NPH insulins treatment twice a day and were examined every 2 weeks for 2 months (visits 1–4), and every 4 weeks for up to 4 additional months (visits 5–8). Clinical signs and SFC were recorded at each visit. Polyuria and polydipsia (PU/PD) were scored as absent (0) or present (1). Results: Median (range) PU/PD scores of combined visits 5–8 (0, 0–1) were significantly lower than median scores of combined visits 1–4 (1, 0–1, p = 0.03) and at enrolment (1, 0–1, p = 0.045). Median (range) SFC of combined visits 5–8 (512 mmol/L, 401–974 mmol/L) was significantly lower than SFC of combined visits 1–4 (578 mmol/L, 302–996 mmol/L, p = 0.002) and at enrolment (662 mmol/L, 450–990 mmol/L, p = 0.03). Lispro insulin dose was significantly and negatively, albeit weakly, correlated with SFC concentration during visits 1 through 8 (r = –0.3, p = 0.013). Median duration of follow up was 6 months (range 0.5–6) and most dogs (8, 66.7%) were followed for 6 months. Four dogs withdrew from the study within 0.5–5 months because of documented or suspected hypoglycaemia, short NPH duration or sudden unexplained death. Hypoglycaemia was noted in 6 dogs. Conclusions: Long-term lispro and NPH combination therapy may improve clinical and biochemical control of some diabetic dogs with comorbidities. Risk of hypoglycaemia should be addressed with close monitoring.