School of Veterinary Science, University of Queensland, Queensland, QLD, Australia; Australian Pet Welfare Foundation, Brisbane, QLD, Australia
In newly diagnosed diabetic cats it is important to achieve good glycemic control early, as it allows for faster resolution of β-cell dysfunction associated with glucose and lipo-toxicity, and increases the probability of remission. Insulin administration facilitates recovery of β-cell dysfunction by minimising hyperglycemia, thus facilitating the return of endogenous secretion of insulin. Treatment with insulin is reported to be the most successful way to achieve good blood glucose control and give the best chance of obtaining remission.
The use of glargine has been shown to achieve significantly higher remission rates compared to PZI or lente insulin. One study comparing remission rates between three different insulins found that 100% of cats enrolled which were treated with glargine achieved remission within 4 months of treatment, compared to 25% of cats receiving lente and 38% of cats receiving PZI. All cats were fed a low-carbohydrate, high-protein canned food with approximately 6% of energy from carbohydrate.
Another retrospective study investigated 90 cats which received either glargine or PZI in combination with a low-carbohydrate diet. Of cats surviving to discharge, use of glargine was more likely to result in remission compared to the use of PZI (72% versus 56% remission rate). The importance of implementing excellent glycaemic control early is demonstrated in a study of diabetic cats where owners followed an insulin dosing protocol aimed at intensive blood glucose control using glargine, home blood glucose monitoring and a low-carbohydrate diet. In that study, cats previously treated with other insulin but started in the intensive programme within 6 months of diagnosis had a remission rate of 84%, compared to a remission rate of 35% for cats started on the program longer than six months after diagnosis, despite excellent glycemic control being achieved with the program. This highlights the importance of early institution of rigorous glycemic control in increasing the probability of remission. A similar study involving intensive control of blood glucose using detemir (Levemir; Novo Nordisk) and home monitoring found almost identical results (81% remission rate in cats changed to the intensive protocol within 6 months of diagnosis and 42% if changed later).
Diet has been reported to be an important management factor contributing to remission in diabetic cats, studies achieving good remission rates have used a combination of insulin and a low-carbohydrate diet. However, the highest remission rates (>80%) have only been reported using a diet with approximately <6% of metabolizable energy from carbohydrate, along with glargine or detemir. While in humans a high-fibre diet has been reported to improve glycaemic control, in cats low-carbohydrate diets with low-moderate fibre have been associated with higher remission rates compared to a moderate-carbohydrate and high-fibre diet. However, further studies are required to evaluate the benefit of increasing fibre in low-carbohydrate diets.
Frequent monitoring of blood glucose concentrations and appropriate adjustment of insulin dose are likely important in achieving remission. In the three studies achieving remission rates >80%, blood glucose was either monitored daily by clients or weekly by the veterinarian in the initial stabilization period. In two studies, owners measured blood glucose a minimum of three times daily and averaged 5 times daily in the initial stabilisation period. In the other study, cats were initially monitored for 3 days in the hospital and then weekly with serial blood glucose measurements in hospital over 12 hours during the stabilization phase. In all three studies, dosing algorithms were used which aimed to achieve rigorous glycemic control, and dose was increased if peak blood glucose concentration was greater than 10 mmol/L (180 mg/dl) or above normal fasting glucose concentrations.
In summary, early institution of excellent glycemic control with long-acting insulin (glargine or detemir), a low-carbohydrate diet and appropriate insulin adjustment based on frequent monitoring of blood glucose, ideally at home, is associated with the highest remission rates in newly diagnosed diabetic cats.