Comparison of continuous glucose monitoring profiles during the day and night in healthy and diabetic cats

Abstract

Objectives: This study aimed to detect hypoglycaemia episodes and evaluate glucose dynamics and glycaemic variability in insulin-treated diabetic and healthy cats using a continuous glucose monitoring system (CGMS). Blood glucose curves are useful for managing insulin-dependent diabetes mellitus (DM) but may miss the nadir and peak. Methods: A CGMS with a 7-day recording period (range 2.2–22.2 mmol/l) was implanted in six healthy and 10 insulin-treated diabetic cats to obtain 24-h glucose curves. For each cat, mean, minimum and maximum glucose concentration, SD and coefficient of variation (CV) were calculated for the daytime and night-time. Results: Most diabetic cats removed sensors prematurely, but 24-h curves were obtained in all; the only adverse effect of the device was mild local skin irritation. In healthy cats, nights had higher SD (0.6 mmol/l [range 0.2–0.8] vs 0.4 mmol/l [range 0.2–0.6]; P = 0.037) and CV (13% [range 5–23] vs 10% [range 4–16]; P = 0.041) compared with the days; mean, minimum and maximum glucose concentration showed no diurnal-nocturnal differences. In diabetic cats, no differences were observed for mean, minimum and maximum glucose concentrations, SD and CV. Hypoglycaemia episodes (<3.5 mmol/l) occurred in five healthy and four diabetic cats, either during the day or night. Compared with well-controlled diabetic cats, those with moderate to poor control had higher mean and maximum glucose concentrations during the 24 h and had higher SD during the day than at night. Conclusions and relevance: Continuous glucose monitoring revealed increased nocturnal glycaemic variability in healthy cats but not in diabetic cats. Furthermore, cats with moderately to poorly controlled DM had higher diurnal glycaemic variability than those well controlled. Low glucose concentrations occurred in both groups and at any time, emphasising the benefit of 24-h glucose curves in diabetic cats.