Beta cell and insulin antibodies in treated and untreated diabetic cats

Beta cell and insulin antibodies are involved in the pathogenesis of diabetes in human patients. Beta cell antibodies have also been found in about 50% of newly diagnosed diabetic dogs. This study's objective was to examine these antibodies' role in feline diabetes. The serum of 26 newly diagnosed untreated diabetic cats, 29 cats on insulin therapy, 30 cats with diseases other than diabetes, and 30 healthy cats was examined for beta cell and insulin antibodies. For beta cell antibody testing, purified beta cells from a radiation-induced transplantable rat insulinoma were used. Serum from cats in which anti-beta cell antibodies were induced by injecting a purified beta cell suspension subcutaneously was used as a positive control. Following incubation with test sera, fluorescein-labeled anti-cat immunoglobulins were used to visualize binding between the beta cells and cat gamma globulins. Each serum was tested on two different tumor preparations. For the detection of insulin antibodies, a charcoal separation method was used. It was found that none of the healthy cats, none of the newly diagnosed, untreated diabetic cats and none of the cats with diseases other than diabetes had antibodies against beta cells or against endogenous insulin. Four diabetic cats (14%) that had been treated with different insulin preparations had insulin antibodies.It is concluded that immune-mediated processes are not causing diabetes in the cat. Further studies are needed to evaluate if antibodies directed against exogenous insulin alter the response of diabetic cats to insulin.     

Retrospective evaluation of continuous rate infusion of regular insulin intravenously for the management of feline diabetic ketoacidosis

The use and efficacy of continuous rate infusion (CRI) of regular insulin intravenously for the treatment of feline diabetic ketoacidosis was retrospectively evaluated. The study focused on the rate of glucose decline, time to resolution of inappetence, time to long-term injectable insulin, and length of hospital stay. Review of medical records from 2009 to 2011 identified 10 cases that met the inclusion criteria. Six cats were existing diabetics, 3 of whom had recent insulin changes. Five cats had concurrent diseases. The mean time to long-term injectable insulin was 55 hours. The mean length of hospitalization was 3.8 days. Five cats survived to discharge. In 5 patients, an insulin CRI permitted a short hospital stay and transition to long-term injectable insulin. Many cats with diabetic ketosis or diabetic ketoacidosis are prior diabetics with concurrent disease and/or a history of recent insulin changes.     

Case presentation from small animal medicine. Diabetes mellitus in a cat]

This case report is about a 9 year old female spayed domestic shorthair cat with a previously diagnosed diabetes mellitus. After an insulin treatment for a short period of time, the cat was given an oral hypoglycemic agent. Four years after initiating therapy the cat was presented with diabetic ketoacidosis. Various aspects of the etiology, pathophysiology and treatment of diabetic ketoacidosis are discussed.     

Pharmacology of a 40 IU/ml porcine lente insulin preparation in diabetic cats: findings during the first week and after 5 or 9 weeks of therapy.

The aim of this study was to measure the pharmacokinetics and pharmacodynamics of subcutaneously injected 40 IU/ml porcine lente insulin preparation (Caninsulin, Intervet BV, The Netherlands) in diabetic cats. The pharmacological properties of the insulin in poorly controlled or untreated cats were compared with those after several weeks of treatment, to determine if improved diabetic stability altered the pharmacology of this insulin. In addition, the pharmacological properties of intravenously injected 100 IU/ml regular porcine insulin (Actrapid MC, NovoNordisk, Denmark) were measured. Serial plasma samples were collected after subcutaneous injection of porcine lente insulin from 25 diabetic cats in the first week of admission to a 12-month diabetic treatment trial. Samples were also collected after 4 or 8 weeks of treatment, in those cats which had not achieved diabetic remission by this time. At this time, serial plasma samples were also collected from these cats after intravenous injection of porcine regular insulin. Plasma samples were assayed for glucose, anti-insulin antibodies were extracted using a PEG technique, and samples were assayed for insulin using an RIA kit with low sensitivity for endogenous feline insulin, but high sensitivity for exogenous porcine insulin in feline plasma. Caninsulin injected subcutaneously in diabetic cats led to a peak insulin concentration in plasma after 1.7+/-0.1 h, and a nadir of blood glucose after 4.1+/-0.3 h. Insulin and glucose concentrations returned to baseline within 12 h. There was no significant change in the onset or duration of Caninsulin action between the first week of treatment and 5 or 9 weeks of treatment. Actrapid MC injected intravenously had a peak insulin at 0.36+/-0.03 h, and a nadir of blood glucose at 1.9+/-0.3 h. Insulin and glucose returned to baseline within 6 h. It was concluded that Caninsulin injected subcutaneously has suitable pharmacological properties for the twice-daily treatment of diabetes mellitus in cats. In addition, Actrapid MC insulin injected intravenously has suitable pharmacological properties for injection every 4-6 h in diabetic cats.     

Hyperglycemic, hyperosmolar syndrome in feline diabetics: 17 cases (1995–2001)

Objective: The purposes of this study were to characterize the hyperglycemic, hyperosmolar syndrome (HHS), also known as nonketotic hyperosmolar diabetes, in cats; to determine the prevalence of HHS in the diabetic cat population in the emergency room; to document the outcome in cats with HHS; and to identify any predisposing factors or predictors of survival. Design: Retrospective study. Setting: An emergency service at a veterinary teaching hospital located in a major metropolitan area. Animals: The case records of 17 cats with hyperglycemic, hyperosmolar syndrome presenting from 1995 to 2001 were evaluated. An additional 37 cats with diabetic ketoacidosis and 80 cats with diabetes mellitus served as comparison groups. Interventions: None. Measurements and main results: Signalment, history, physical examination findings, clinico‐pathologic data, concurrent disease, and outcome were recorded. Hyperglycemic, hyperosmolar syndrome was seen in older cats that were often long‐standing diabetics receiving insulin for many months. Client concerns included polydipsia, polyuria, and lethargy. Neurologic and respiratory signs occurred frequently. Evaluation at presentation revealed profound dehydration, lactic acidosis, and azotemia. Serious concurrent diseases that likely contributed to the development of the HHS crisis were diagnosed in 88% (15/17) of the HHS cats. The most common concurrent diseases were renal failure, respiratory compromise, infection, congestive heart failure, neoplasia, and gastrointestinal tract disease. Pancreatitis and hepatic disease did not occur frequently in this diabetic cat population. Sixty‐five percent of HHS cats did not survive the initial hospitalization, with most dying or being euthanized within 10 hours of presentation. The long‐term survival rate was low (12%). Conclusions: HHS is a serious life‐threatening form of diabetic crisis and cats with HHS often have other severe systemic diseases. Cats with diabetes and concurrent disease, especially renal failure and congestive heart failure, are at increased risk of HHS and should be closely monitored for signs of crisis. The mortality rate for HHS cats is high.     

Anti-insulin antibodies in dogs with naturally occurring diabetes mellitus

The presence of anti-insulin antibodies was determined by ELISA in serum samples from 30 diabetic dogs receiving bovine insulin therapy and 30 normoglycaemic dogs. Twenty of the diabetic dogs had significant reactivity to both bovine (heterologous) and porcine (homologous) insulin compared to control dogs. In contrast there was no significant difference between the two populations in reactivity to canine distemper virus (CDV) or canine thyroglobulin. The high degree of correlation between anti-bovine insulin and anti-porcine insulin antibodies suggested cross-reactivity which was confirmed by performing a competition ELISA, with antibody binding to bovine insulin inhibited by pre-incubating serum with porcine insulin. The insulin B-chain, rather than the A-chain was the most reactive component of the insulin molecule although in some cases, diabetics with antibody reactivity to whole insulin protein showed minimal reactivity to the individual subunits. The data suggest that treatment of diabetic dogs with bovine insulin can lead to anti-insulin antibody production. These antibodies cross-react with homologous insulin and recognise conformational as well as linear epitopes.     

Food intake and blood glucose in normal and diabetic cats fed ad libitum

Ten diabetic cats were studied at intervals for up to 12 months with twice-daily insulin injections. Ten clinically healthy cats were also studied. Diets fed were based on the individual cat's performance, using mainly commercial dry or canned cat foods and fresh meat. In most cases more than one food was offered. Food was given fresh twice daily, and the cats allowed to eat ad libitum.The food intake and blood glucose were measured every 2 h in diabetic cats after insulin injection and in diabetic and normal cats without insulin injections. Food was quantified by the energy consumed (kJ ME), crude protein (g), crude fat (g), and carbohydrate (g). The blood glucose in 10 diabetic cats was measured for 2 h following a 20-min meal.Both diabetic cats and normal cats showed similar patterns of eating, with a higher food intake in the 2 h after fresh food was placed. Both groups of cats ate multiple small meals spread through the day and night. There was little or no correlation between the blood glucose and the amount of food consumed over the previous 2-h period, in insulin- or non-insulin-treated diabetic cats, or in normal cats. An overnight fast did not significantly alter morning blood glucose in diabetic cats. No demonstrable appetite stimulation occurred following an occurrence of low blood glucose; however, recorded incidences were few. No post-prandial hyperglycaemia was seen in the 10 diabetic cats during a 2-h period following the ingestion of typical cat foods.     

Insulin therapy in cats with diabetes mellitus

Thirteen cats with diabetes mellitus were evaluated. Clinical signs included polydipsia, polyuria, polyphagia, lethargy, and weight loss. Results of physical examination included obesity, hepatomegaly, mild seborrhea sicca, muscle wasting, and dehydration. One cat walked plantigrade and was suspected of having a diabetic neuropathy. Persistent hyperglycemia, glucosuria, high liver enzyme activities, hypercholesterolemia, hyperproteinemia, and low electrolyte concentrations were the common laboratory findings. In 3 cats diabetes mellitus developed after megestrol acetate therapy; 2 of these cats required only temporary insulin treatment. In a 3rd cat, which had no history of receiving diabetogenic drug therapy, remission of diabetes mellitus also was observed. Serum insulin and plasma glucose concentrations were determined in 6 cats after administration of an intermediate-acting insulin (isophane insulin) and in 3 cats after administration of a long-acting insulin (protamine zinc insulin). The insulin concentration peaked 2 to 6 hours after the injection of intermediate-acting insulin and 6 to 12 hours after the injection of long-acting insulin. The lowest glucose concentration was recorded 4 to 8 hours after injection of intermediate-acting insulin, and 6 to 12 hours after injection of long-acting insulin. It was concluded that, although insulin therapy must be adjusted to the individual, the diabetic cat usually requires twice-daily administration of isophane insulin; however, the protamine zinc insulin can be given once daily for satisfactory control.     

Remission of Diabetes Mellitus in Cats with Diabetic Ketoacidosis

Background: Diabetic ketoacidosis (DKA) has long been considered a key clinical feature of type‐1 diabetes mellitus (DM) in humans although. An increasing number of cases of ketoacidosis have been reported in people with type‐2 DM. Hypothesis/Objectives: Cats initially diagnosed with DKA can achieve remission from diabetes. Cats with DKA and diabetic remission are more likely to have been administered glucocorticoids before diagnosis. Animals: Twelve cats with DKA and 7 cats with uncomplicated DM. Methods: Retrospective case review. Medical records of cats presenting with DKA or DM were evaluated. Diabetic remission was defined as being clinically unremarkable for at least 1 month after insulin withdrawal. The cats were assigned to 1 of 3 groups: (1) cats with DKA and diabetic remission; (2) cats with DKA without diabetic remission; and (3) cats with DM and diabetic remission. Results: Seven cats with DKA had remission from diabetes. These cats had significantly higher concentrations of leukocytes and segmented neutrophils, and significantly lower concentrations of eosinophils in blood and had pancreatic disease more often than did cats with uncomplicated DM and diabetic remission. With regard to pretreatment, 3/7 cats in group 1, 1/5 cats in group 2, and 1/7 cats in group 3 had been treated with glucocorticoids. Conclusions and Clinical Importance: Remission of DM in cats presenting with DKA is possible. Cats with DKA and remission have more components of a stress leucogram, pancreatic disease, and seemed to be treated more often with glucocorticoids than cats with uncomplicated DM and diabetic remission.     

Rebound hyperglycemia following overdosing of insulin in cats with diabetes mellitus

Posthypoglycemic hyperglycemia (rebound hyperglycemia) after overdosing of insulin was diagnosed in 6 cats with diabetes mellitus. Administration of excessive insulin induced hypoglycemia within 4 to 8 hours, followed by rebound hyperglycemia. Diagnosis was made by serial blood glucose determinations during a 20- to 24-hour period after insulin administration. Four cats had a history of difficulty in regulating the diabetic state. In 2 cats, rebound hyperglycemia was diagnosed on routine serial blood glucose determinations. All of the cats were hyperglycemic for most of the day. Rebound hyperglycemia was observed with both intermediate (neutral protamine hagedorn) and long-acting (protamine zinc iletin) insulins, and the range of insulin doses at which the disorder developed overlapped previously determined therapeutic doses for these insulins in the cat. Urine glucose and single afternoon blood glucose determinations were inadequate and potentially misleading in monitoring diabetic cats receiving excessive amounts of insulin.     

Evaluation of the oral antihyperglycemic drug metformin in normal and diabetic cats

Metformin is an oral antidiabetic drug that improves control of glycemia primarily by inhibiting hepatic gluconeogenesis and glycogenolysis. This study evaluated the usefulness of metformin for the treatment of diabetes mellitus in cats. The study consisted of 3 phases. Phase I was a dose-finding study performed in healthy cats that were randomly administered varying doses of metformin to determine the approximate dose that would yield plasma concentrations known to be effective in humans. Phase 2 was a 3-week safety study performed in healthy cats to determine if cats could tolerate the daily oral dose and administration protocol identified during phase 1. Phase 3 was a clinical trial evaluating the clinical response of diabetic cats to oral metformin treatment. Five cats with newly diagnosed, naturally acquired diabetes mellitus were enrolled in phase 3. Plasma metformin concentrations in the therapeutic range of 0.5-2 microg/mL were achieved with doses of 50 mg/cat PO q12h without dramatic drug accumulation. Intermittent lethargy, inappetence, vomiting, and weight loss were identified, and the results of the CBC, serum biochemical analysis, plasma lactate concentration, and urinalysis remained within the reference range during phase 2 of the study. During phase 3, control of glycemia was achieved in 1 of 5 diabetic cats after 8 weeks of metformin treatment; 3 cats failed to respond to metformin, and treatment with insulin was initiated after 7-8 weeks of metformin treatment; 1 cat died unexpectedly 11 days after starting metformin treatment. The cause of death was not determined. The serum insulin concentration was within or greater than the reference range in the responder diabetic cat and was undetectable or at the low end of the reference range in the nonresponder diabetic cats. The results of this study suggest that metformin is beneficial only in those diabetic cats with detectable concentrations of insulin at the time metformin treatment is initiated.     

Transient clinical diabetes mellitus in cats: 10 cases (1989-1991)

Medical records of 10 cats with transient clinical diabetes mellitus were reviewed. At the time diabetes was diagnosed, clinical signs included polyuria and polydipsia (10 cats), weight loss (8 cats), polyphagia (3 cats), lethargy (2 cats), and inappetence (1 cat). Mean (+/- SD) fasting blood glucose concentration was 454 +/- 121 mg/dL, mean blood glucose concentration during an 8-hour period (MBG/8 hours) was 378 +/- 72 mg/dL, and glycosuria and trace ketonuria were identified in 10 and 5 cats, respectively. Baseline serum insulin concentration was undetectable (6 cats) or within the reference range (4 cats) and serum insulin concentration did not increase after i.v. glucagon administration in any cat. Insulin-antagonistic drugs were being administered to 5 cats and concurrent disorders were identified in all cats. Management of diabetes included administration of glipizide (6 cats), insulin (3 cats), or both (1 cat), discontinuation of insulin-antagonistic drugs, and treatment of concurrent disorders. Insulin and glipizide treatment was discontinued 4-16 weeks (mean, 7 weeks) after the initial diagnosis of diabetes was confirmed. At the time treatment for diabetes was discontinued, clinical signs had resolved, mean fasting blood glucose concentration was 102 +/- 48 mg/dL, MBG/ 8 hours was 96 +/- 32 mg/dL, glycosuria and ketonuria were not identified in any cat, and concurrent disorders (except mild renal insufficiency in 1 cat) had resolved. Significant (P < .05) increases occurred in postglucagon serum insulin concentrations, insulin peak response, and total insulin secretion, compared with values obtained when clinical diabetes was diagnosed. Histologic abnormalities were identified in pancreatic islets of 5 cats in which pancreatic biopsies were obtained and included decreased number of islets (4 cats), islet amyloidosis (3 cats), and vacuolar degeneration of islet cells (3 cats). Mean beta cell density was significantly (P < .001) decreased in diabetic cats compared with control cats (1.4 +/- 0.7 versus 2.6 +/- 0.5%, respectively). Cells within islets stained positive for insulin, however, the number of insulin-staining cells per islet and the intensity of insulin staining were decreased in 5 and 2 cats, respectively. Clinical diabetes had not recurred in 1 cat after 6 years, in 4 cats lost to follow-up after 1.5, 1.5, 2.0, and 2.5 years, and in 2 cats that died 6 months and 5.5 years after clinical diabetes resolved. Clinical diabetes recurred in 3 cats after 6 months, 14 months, and 3.4 years, respectively. These findings suggest that cats with transient clinical diabetes have pancreatic islet pathology, including decreased beta cell density, and that treatment of diabetes and concurrent disorders results in improved beta cell function, reestablishment of euglycemia, and a transition from a clinical to subclinical diabetic state.     

Diagnostic utility of glycosylated hemoglobin concentrations in the cat

Changes in glycosylated hemoglobin (GHb) concentrations, K values (% disappearance of glucose/min after an intravenous injection of 1 g/kg dextrose), and blood glucose concentrations were examined in eight cats before and during the induction of diabetes, and in four of these cats after they were placed on insulin treatment. There was a statistically significant separation of GHb, K values, and fasting blood glucose concentrations between healthy and diabetic cats. Changes in GHb correlated best with the K value and single weekly fasting glucose concentrations averaged over eight periods for each cat while diabetes was induced (R = 0.80 and 0.78, respectively); however, fasting blood glucose concentrations obtained on the day of the GHb measurement were also highly correlated (R = 0.69; P < 0.001). The correlation between GHb and single weekly glucose concentrations obtained in insulin-treated cats at the time of insulin peak action and averaged over an 8-wk time period for each cat was less but still significant (R = 0.53; P < 0.001). It is concluded that GHb measurements are a simple and reliable way to monitor changes in glucose control in the diabetic cat over a prolonged period.     

Anti-insulin antibodies in diabetic dogs before and after treatment with different insulin preparations

Background: Anti‐insulin antibodies (AIA) occur in diabetic dogs after insulin therapy, although their clinical significance is unclear. Hypothesis: Treatment of diabetic dogs with heterologous insulin is more likely to stimulate production of AIA than is treatment with homologous insulin. Animals: Diabetic dogs sampled before insulin therapy (n = 40), diabetic dogs sampled following treatment with porcine (homologous) insulin (n = 100), bovine (heterologous) lente insulin (n = 100), or bovine protamine zinc (PZI) insulin (n = 20), and nondiabetic control dogs (n = 120). Methods: Prospective observational study. Sera were analyzed by ELISA for antibodies against porcine insulin, bovine insulin, insulin A, B, or C peptides, and control antigens; canine distemper virus (CDV) and canine thyroglobulin (TG). Canine isotype‐specific antibodies were used to determine total and anti‐insulin IgG1 : IgG2 ratios. Results: There was no difference in CDV or TG reactivity among the groups. AIA were detected in 5 of 40 newly diagnosed (untreated) diabetic dogs. There was no significant difference in AIA (ELISA optical density reactivity) comparing control and porcine insulin‐treated diabetic dogs (P > .05). Anti‐insulin reactivity was most prevalent in bovine PZI insulin‐treated dogs (90%; P < .01), and bovine lente insulin‐treated dogs (56%; P < .01). AIA induced by treatment were enriched for the IgG1 isotype. Conclusions and Clinical Importance: This study indicates that bovine insulin is more immunogenic than porcine insulin when used for treatment of diabetic dogs.     

Feline insular amyloid: immunohistochemical and immunochemical evidence that the amyloid is insulin-related

Utilizing islet amyloid-laden pancreatic tissues from six diabetic cats, we demonstrated substantial immunoreactivity (peroxidase-antiperoxidase technique) of the islet amyloid with antiserum to a B chain-rich insulin fraction, but no reactivity with antisera to insulin, glucagon, or somatostatin. Islet amyloid was purified from two cats and a protein unique to the diabetic and islet amyloid-laden cats was separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Immunoreactivity of this protein with antiserum to the B chain-rich insulin fraction was also shown by immunoblotting. Attempts to obtain the amino acid composition of the purified unique protein (represented by a single 25,000 dalton band on gel electrophoresis) were not successful because the amount of protein was too small. These results provide important additional evidence that an insulin-related protein is involved in the formation of islet amyloid. Our study also shows that the diabetic cat provides several advantages for the continued study of the etiopathogenic relationship of islet amyloid and diabetes mellitus.     

Diabetic cataracts: different incidence between dogs and cats

Diabetes mellitus is one of the most common endocrinopathies in the dog and cat. Diabetic cataract primarily affects the canine species and is rarely observed in the cat. It has been proposed that the incidence of cataracts in diabetic dogs is high because many of these patients have significant hyperglycemia despite insulin therapy. Age, gender, levels of serum glucose (before and during insulin therapy) and cataract formation were evaluated, retrospectively, in 23 dogs and 22 cats with diabetes mellitus. In the canine population, the groups with the highest frequency of presentation were females and sexually intact animals. In contrast, males and neutered animals were the most prevalent groups in the feline diabetic population. Over 80% of diabetic cats and dogs were older than 7 years. Our results confirm the almost total lack of cataracts in diabetic cats, while they were present in more than half of the dogs. A relation between the incidence of cataracts and the correspondent level of hyperglycemia in the canine and feline species could not be established. The estimation of the relative risk for the development of cataracts in diabetic dogs shows that some population groups have a higher probability for suffering from this ocular alteration. A relation between relative risk and the correspondent level of hyperglycemia in the various groups was not found. This fact indicates that other factors are involved in the unequal appearance of diabetic cataracts in dogs and cats.     

Comparison of regular insulin infusion doses in critically ill diabetic cats: 29 cases (1999–2007)

Objective – To compare biochemical parameters, neurologic changes, length of hospital stay, and clinical improvement in 3 groups of cats with diabetic ketosis/diabetic ketoacidosis (DK/DKA) prescribed varied doses of regular insulin as a continuous rate of infusion (CRI). Design – Retrospective study. Setting – University teaching hospital. Animals – Twenty‐nine client‐owned cats with DK/DKA prescribed a regular insulin CRI. Interventions – Cats were grouped as follows: 7 cats each in Group 1 and 2, (prescribed 1.1 and 2.2 U/kg/d, respectively), and 15 cats in Group 3 (prescribed increasing doses as needed). Measurements and Main Results – None of the groups received the total prescribed dose of insulin. The mean actual dose administered/kg/d ranged from 0.30 (0.21) to 0.87 (0.32) U/kg/d in Groups 1, 2, and 3. There was no difference in mean minimum blood glucose (BG) per 4 hours or change in BG from baseline per 4 hours between Groups 1 and 2 (P=0.63, 0.50). There was no difference between groups regarding the time required to reach a BG ≤13.9 mmol/L (250 mg/dL), serum phosphorus or potassium concentrations relative to baseline values (P=0.53, 0.90), length of time until urine or serum ketones were no longer detected (P=0.73), the animal commenced eating (P=0.24), or length of hospital stay (P=0.63). Four of the cats had declining mentation during hospitalization; there were no relationships between osmolality at presentation, either prescribed or administered insulin dose, and mentation changes. Three of the 4 cats with declining mentation survived. Twenty‐seven of the 29 cats (93%) survived to discharge. Conclusions – In this study, prescribing the published canine dose (2.2 U/kg/d) of regular insulin to cats with DK/DKA does not appear to increase the frequency of adverse neurologic or biochemical sequelae compared with cats that are prescribed the published cat dose (1.1 U/kg/d). The use of a sliding scale for determination of infusion rates significantly reduces the amount of insulin cats receive in this setting. Determination of whether adverse sequelae would occur more frequently if cats with DK/DKA received the full insulin prescribed doses of 1.1, 2.2, or >2.2 U/kg/d is warranted. Further controlled studies are necessary to determine if higher doses of insulin are associated with beneficial effects on morbidity or mortality.     

Feline diabetes mellitus: low carbohydrates versus high fiber?

Treatment of diabetes mellitus (DM) in the cat relies primarily on the adequate insulin therapy and controlled dietary intake. The goals of managing DM in the cat have changed from attaining glycemic control to achieving diabetic remission (transient diabetes) in a large proportion of cases. Remission rates of up to 68% have been published. The used of low-carbohydrate foods for cats improves the odds of achieving diabetic remission by fourfold. Nonetheless, some cats show an improved response to high-fiber food. Clinical judgement, trial, and personal preference to currently dictate which diet to offer an individual animal.     

Suppression of cortisol responses to exogenous adrenocorticotrophic hormone, and the occurrence of side effects attributable to glucocorticoid excess, in cats during therapy with megestrol acetate and prednisolone.

The major purpose of this investigation was to determine the effect of prednisolone and megestrol acetate in cats on the adrenal cortisol response to exogenous adrenocorticotrophic hormone during drug administration at dose rates employed for management of some inflammatory feline dermatoses. Prednisolone (at least 2 mg/kg/day) and megestrol acetate (5 mg/cat/day) were each administered orally to seven cats from days 1 to 16. Three additional cats received no therapy. Basal and stimulated cortisol concentrations, food and water intake, hematology, blood biochemistry, urinalyses, and hepatic and cutaneous histology were studied in all cats before, during, and two weeks following the end of treatment. Cats given prednisolone or megestrol acetate had significant suppression of stimulated cortisol levels on day 8. This change was more marked on day 15, when the suppression in cats given megestrol acetate was also significantly more severe than in those receiving prednisolone. Recovery of adrenal reserve was considered present on day 30 in six of seven cats given prednisolone, but in only three of seven receiving megestrol acetate. Eosinopenia, glycosuria and hepatocyte swelling from glycogen deposition were occasionally recorded in treated cats of both groups, providing additional circumstantial evidence for glucocorticoid activity of megestrol acetate in cats. It is advised that abrupt withdrawal of prednisolone or megestrol acetate therapy be avoided in this species to reduce the chance of precipitating clinical signs of hypoadrenocorticism, even after treatment for as little as one week.     

Investigation of serum IGF-I levels amongst diabetic and non-diabetic cats

Since insulin-like growth factor-I (IGF-I) was first discovered as a mediator of glucose homeostasis, it has been extensively investigated in diabetes research in humans, rodents and primates. To date, however, relatively little work has been carried out on this hormone in the cat, despite the pathophysiological similarities between human and feline diabetes mellitus, as well as the relatively common nature of the disease in cats. This study reports on the IGF-I concentrations of 42 insulin treated diabetic cats and 25 normal cats. Diabetic subjects were grouped according to length of insulin treatment as either short, medium or long term. Analysis of variance (ANOVA) and Fischer's pair-wise comparisons revealed that mean IGF-I levels in short-term diabetic cats were significantly lower than those in normal cats whilst mean levels in long-term diabetics were significantly higher. The direction and extent of these alterations may have implications for our understanding of the pathophysiology of feline diabetes mellitus and for the use of this hormone in the diagnosis of acromegaly in diabetic cats.