Current understanding of feline diabetes: Part 1, pathogenesis

Type-1 diabetes, resulting from immune-mediated destruction of beta cells, appears to be rare in cats. Type-2 diabetes, characterised by inadequate insulin secretion and impaired insulin action, is the most common form of diabetes in cats. Other specific forms of diabetes constitute a substantial minority of cases. The most common is pancreatic destruction from pancreatic adenocarcinoma. Less frequent causes are insulin resistance from other endocrinopathies including acromegaly. Diabetes in cats is characterised by variable loss of insulin secretory capacity and insulin resistance. Glucose toxicity, islet amyloid-deposition, and pancreatitis contribute to further loss of beta cells and failure of insulin secretion. A significant number of cats undergo remission of their diabetes, usually 1-3 months after good glycaemic control is instituted. Obesity, old age, and Burmese breed are recognised risk factors for the development of diabetes in cats

Feline Diabetes mellitus: Clinical use of long-acting glargine and detemir

Practical relevance: Diabetes mellitus is a common endocrine disorder in feline practice, affecting approximately 1 in 200 cats. The majority of diabetic cats have type 2 diabetes mellitus, which results from a combination of peripheral insulin resistance and a progressive reduction in insulin production. Clinical challenges: While usually easy to diagnose, management of diabetes mellitus presents a number of challenges for practitioners and clients alike. Practitioners must decide on diet, insulin type and dose, monitoring method and intensity, and concomitant therapy, which will vary based on individual patient and client needs, and geographic location. Practitioners may also encounter patients with diabetic ketoacidosis or other diabetic complications, and patients with multiple concurrent diseases. Clients may be challenged by the substantial time and financial commitment involved in owning a diabetic cat. Audience: Understanding the pathophysiology, optimal treatment protocols and current goals of diabetes management will benefit practitioners managing diabetic cats. This article reviews the most current management plans for feline diabetics. It places particular emphasis on best practice for achieving diabetic remission, which is an attainable goal in the majority of newly diagnosed diabetic cats. Evidence base: The information in this article is drawn from the recent human and veterinary literature, including prospective and retrospective studies. The body of prospective clinical data on the use of newer, long-acting insulins (glargine and especially detemir) in cats is limited, but growing

Current understanding of feline diabetes: Part 2, treatment

When treating diabetic cats, the primary aim is to control clinical signs without causing clinical hypoglycaemia. Secondary goals are to maximise the chances of attaining diabetic remission and to minimise the risk of complications due to chronic hyperglycaemia. A treatment plan that is convenient for the owner is important for compliance. Underweight or overweight diabetic cats should be fed with the aim of normalising bodyweight. Current evidence suggests that non-obese diabetic cats can be fed ad libitum. The oral hypoglycaemic drug glipizide is well established as a treatment for about a third of diabetic cats, which have residual beta cell function. Preliminary studies on other oral agents such as vanadium salts, metformin, and troglitazone indicate a potential use in some diabetic cats. Insulin treatment remains the treatment of choice for the majority of diabetic cats. Choice of insulin, dose rates and monitoring of treatment are discussed

Plasma leptin concentrations are independently associated with insulin sensitivity in lean and overweight cats

This study investigated relationships between plasma leptin, insulin concentrations, insulin sensitivity and glucose tolerance in lean and overweight cats. Leptin concentrations were measured in 16 cats during glucose tolerance tests before and after gaining weight, and after feeding a test meal in overweight cats. An important finding of this study is that in both lean (r = 0.79) and overweight (r = -0.89) cats, the higher the leptin concentrations, the more insulin resistant the cat, independent of the degree of adiposity. Leptin concentrations at baseline and after consuming a meal tended to be higher in overweight cats with glucose intolerance, compared to overweight cats with normal glucose tolerance, although the difference was not significant. After feeding the test meal to overweight cats in the early morning, plasma leptin concentrations initially decreased before subsequently rising to peak 15 h later, which coincided with late evening. The leptin peak occurred 9 h after the insulin peak following ingestion of the test meal. Importantly, this study suggests that increased leptin concentrations may contribute to the diminished insulin sensitivity seen in overweight cats. Alternatively, the compensatory hyperinsulinaemia found with insulin resistance in overweight cats could stimulate leptin production. (C) 2002 Published by Elsevier Science Ltd on behalf of ESFM and AAFP

Dietary chromium tripicolinate supplementation reduces glucose concentrations and improves glucose tolerance in normal-weight cats

The effect of dietary chromium supplementation on glucose and insulin metabolism in healthy, non-obese cats was evaluated. Thirty-two cats were randomly divided into four groups and fed experimental diets consisting of a standard diet with 0 ppb (control), 150 ppb, 300 ppb, or 600 ppb added chromium as chromium tripicolinate. Intravenous glucose tolerance, insulin tolerance and insulin sensitivity tests with minimal model analysis were performed before and after 6 weeks of feeding the test diets. During the glucose tolerance test, glucose concentrations, area under the glucose concentration-time curve, and glucose half-life (300 ppb only), were significantly lower after the trial in cats supplemented with 300 ppb and 600 ppb chromium, compared with values before the trial. Fasting glucose concentrations measured on a different day in the biochemistry profile were also significantly lower after supplementation with 600 ppb chromium. There were no significant differences in insulin concentrations or indices in either the glucose or insulin tolerance tests following chromium supplementation, nor were there any differences between groups before or after the dietary trial. Importantly, this study has shown a small but significant, dose-dependent improvement in glucose tolerance in healthy, non-obese cats supplemented with dietary chromium. Further long-term studies are warranted to determine if the addition of chromium to feline diets is advantageous. Cats most likely to benefit are those with glucose intolerance and insulin resistance from lack of exercise, obesity and old age. Healthy cats at risk of glucose intolerance and diabetes from underlying low insulin sensitivity or genetic factors may also benefit from long-term chromium supplementation. (C) 2002 ESFM and AAFP

Determination of reference values for glucose tolerance, insulin tolerance, and insulin sensitivity tests in clinically normal cats

Objective-To determine reference values and test variability for glucose tolerance tests (GTT), insulin tolerance tests (ITT), and insulin sensitivity tests (IST) in cats, Animals-32 clinically normal cats. Procedure-GTT, ITT, and IST were performed on consecutive days. Tolerance intervals tie, reference values) were calculated as means +/- 2.397 SD for plasma glucose and insulin concentrations, half-life of glucose (T-1/2glucose), rate constants for glucose disappearance (K-glucose and K-itt), and insulin sensitivity index (S-l). Tests were repeated after 6 weeks in 8 cats to determine test variability. Results-Reference values for T-1/2glucose, K-glucose, and fasting plasma glucose and insulin concentrations during GTT were 45 to 74 minutes, 0.93 to 1.54 %/min, 37 to 104 mg/dl, and 2.8 to 20.6 muU/ml, respectively. Mean values did not differ between the 2 tests. Coefficients of variation for T-1/2glucose, K-glucose, and fasting plasma glucose and insulin concentrations were 20, 20, 11, and 23%, respectively. Reference values for K-itt were 1.14 to 7.3%/min, and for S-l were 0.57 to 10.99 x 10(-4) min/muU/ml. Mean values did not differ between the 2 tests performed 6 weeks apart, Coefficients of variation for K-itt and S-l were 60 and 47%, respectively. Conclusions and Clinical Relevance-GTT, ITT, and IST can be performed in cats, using standard protocols. Knowledge of reference values and test variability will enable researchers to better interpret test results for assessment of glucose tolerance, pancreatic beta -cell function, and insulin sensitivity in cats