Continuous glucose monitoring in diabetic cats

Recent technological advances now make it possible for the clinician to easily access continuous glucose monitoring in diabetic cats, as this article describes.

Introduction

Diabetes mellitus (DM) is a common disorder in geriatric cats (1) and appropriate management requires careful monitoring of response to insulin treatment, and in fact good glycemic control can result in diabetic remission in many cases (2-4). The recent introduction of technology that allows continuous monitoring of interstitial glucose has led to major improvements in the veterinarian’s ability to supervise and improve glycemic control in affected animals (5-9).

Type II DM is the most common type of DM in cats; this is characterized by abnormal secretion of insulin from the pancreas in combination with peripheral insulin resistance. Diagnosis is made based on the presence of clinical signs (polyuria, polydipsia, polyphagia and weight loss), and documentation of hyperglycemia and glycosuria (2,3). In cats, the diagnosis is complicated by stress hyperglycemia, so it is important not only to document persistent hyperglycemia and glucosuria, but also to rule out other diseases that may cause similar clinical signs, such as hyperthyroidism and gastrointestinal disease. Treatment of feline DM relies on insulin therapy, dietary modification, management of concurrent illness and weight management, and many type II diabetic cats will achieve remission if insulin treatment results in good glycemic control. Factors that influence the likelihood of remission include the severity of pancreatic pathology, the presence of insulin resistance caused by concurrent illness or medications, obesity, and the ability to feed a low carbohydrate diet (10,11). Progressive loss of beta-cells may ultimately result in progression to type 1 DM, therefore good glycemic control is key to a positive outcome in affected cats.

Insulin therapy

Insulin types

There are three insulin products that are appropriate for first line treatment of feline DM (Table 1); protamine zinc insulin (PZI), lente (porcine insulin zinc suspension) insulin, and glargine insulin, an insulin analogue (3). Detemir (another insulin analogue) can also be used, but is not a first-line choice because of its cost. NPH (neutral protamine Hagedorn) insulin tends to have a very short duration of action in cats, and is not recommended. The starting dose of insulin for a new feline diabetic patient is 1-3 U/cat (0.25-0.5 Unit/kg), and the author recommends the lower end of this dose. Whichever formulation is chosen, twice daily injections are more likely to result in good glycemic control than once a day therapy. If the former is not possible, once daily injections with PZI or glargine can result in effective control of clinical signs in some cats.

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