Feline diabetes
Brief facts
- Diabetes Mellitus is a heterogeneous group of disorders characterized by hyperglycemia and glucose intolerance.
- Diabetes Mellitus, Type 2 (not insulin-responsive or dependent (NIDDM)) is most common diabetes (80-95% cases) in cats. It is characterized initially by insulin resistance and hyperinsulinemia; and eventually by glucose intolerance; hyperglycemia; and overt diabetes. In cats, the disease is usually diagnosed when clinical signs are evident. This occurs when blood glucose concentration exceeds the renal threshold, which is ~16 mmol/l (~288 mg/dl) in healthy cats.
- Evidence for genetic factors in feline diabetes includes the overrepresentation of Burmese and domestic short- and long-hair domestic cats and underrepresentation of some pure breeds. Environmental risk factors include advancing age, obesity, male gender, neutering, drug treatment, and physical inactivity. High-carbohydrate diets increase glucose and insulin levels and may predispose cats in obesity and diabetes.
Overview of risk factors: Pushkin's story
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Pushkin was born in 2000. He was adopted from Humane Society shelter for nominal fee $30.
He is plain vanilla |
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In accordance with the shelter's regulations Pushkin was neutered at tender age of 8-10 weeks. Neutered male cats are considered to be under greater risk of suffering from diabetes. |
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In general, male cats have higher predisposition to diabetes because of several reasons. One of them is tendency to have much lower insulin sensitivity (~37% lower) than females. Low insulin sensitivity (or, in other words, insulin resistance) means that pancreatic β-cells have to produce more insulin for cat's body to allow for effective glucose utilization. At some point, the beta-cells become unable to catch up with ever increasing demands of the body and glucose accumulation in blood begins. At the same time, body cells become unable to uptake the glucose and suffer from energy loss. |
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Pushkin spent a lot of energy when trying to keep balance with this hideous collar made from FedEx envelop. He used the basket for head and body support. |
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Pushkin quickly recovered from the operation. He was agile, active, and strong-willed cat. |
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Pushkin grew very fast. In several months he knew Oxford dictionary very well. |
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After Pushkin learned computer skills he became bored and often fell fast asleep during work hours... |
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Physical inactivity is one of most important risk factors of type 2 diabetes both directly by decreasing insulin sensitivity and indirectly by an effect on body weight. By 1.5-2 years of age Pushkin's belly became visibly round. |
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The evolutionists tried to explain the phenomenon of wide-spread insulin resistance in human as well as in animals. Some interesting theories have been advanced, including the thrifty-gene theory and the carnivore connection theory. Both theories propose that there was evolutionary advantage for individuals who had low insulin sensitivity. Thrifty-gene theory suggests that in times when food was sparse, the insulin resistance helped to maintain sufficient glucose levels in blood as well as to utilize fat accumulated in times when food was plentiful. On the other hand, during excess of food supply, selective resistance to the glucoregulatory but not fat forming effects of insulin, facilitated efficient conversion of the consumed food to fat. |
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In the carnivore connection theory, insulin resistance evolved to maintain normoglycemia on a high-protein, low carbohydrate diet. Normoglycemia is essential for brain function and reproduction, and is achieved by resistance to the glucose-lowering effects of insulin. In both theories, diabetes develops when there is constant supply of easily digestible, highly palatable food, together with physical inactivity. Male cats are especially vulnerable due to higher insulin resistance and inherent predisposition to obesity: when given free access to food males gain weight faster than females. Also males have tendency to have significantly higher fat mass to lean mass ratio. |
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Insulin resistance increases with obesity and physical inactivity. Pushkin is example of both. At some point he reached weight of 10 kg (22 pounds) and his veterinarian diagnosed him as morbidly obese. It did not prevent him from getting a modeling gig and you can see his round, plus size figure on one pretty important webpage. |
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Pushkin started dieting and exercising, and in 3 months after the diagnosis, he managed to loose 0.5 kg. Unfortunately, the diabetes was approaching at faster pace than Pushkin thought and around January, 2009 it struck out. Pushkin started to loose weight rapidly: within 2 months he reached 7.7 kg. In March his health declined. Lethargy, polyuria, bloody discharges, and anorexia ensued. He was rushed to the best veterinarian clinic in the area (Kentlands Veterinary Hospital in Gaithersburg, Maryland). He was diagnosed with full blown diabetes complicated with ketoacidosis, and urinary infection. He got two rounds of antibiotics and started to receive regular insulin injections at home. |
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The pattern of fat deposition in obese individuals also affects the severity of insulin resistance. In humans, abdominal obesity is associated with greater risk of diabetes than peripheral obesity. It was mentioned in one of articles listed below that overweight Burmese cats typically develop abdominal fat rather than subcutaneous fat found in overweight domestic cats. Although Pushkin is a domestic cat, he was unlucky in this area too: he accumulated a lot of belly fat whereas his paws remained very slim. |
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Pushkin is still overweight. He has a lot of work ahead of him. After he got his diabetes under control, his weight increased a little because with help of insulin his body started to metabolize glucose in order to receive necessary energy. He plans to loose weight by dieting and exercise. |
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Well, probably mostly by dieting because he is extremely lazy. He gave up Friskies Fancy Feast, which he loved, and now eats Purina OM dry food, which he hates, lean chicken or beef meat, and, occasionally, shrimp. He tried many times to eat Purina OM wet food but failed to get used to it. Fortunately, he is not a greedy eater. Also, he drinks much less water than before and, respectively, uses his litter box not that often. |
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This is Pushkin 9 years after he was born. He still likes posing for the camera, mostly when lying down. Here he attempts to do it in sitting position but his sleepiness is overwhelming and weighs him down. Please visit Pushkin's lab where you can see how Pushkin's nurse manages to draw blood from his paper-thin ears for analysis, his glucose readings and much more. In glossary you will find terms and concepts that are used in research articles about diabetes. Feline diabetes diagram illustrates complexity of diabetes and how difficult is to control it. |
Pushkin's last picture made on 10/09/2010. Pushkin died on 10/14/2010 from complicaion of diabetes after oral surgery.
References
- Rand JS et al. Canine and feline diabetes mellitus: nature or nurture? J Nutr. 2004 Aug
- Rand J. Current understanding of feline diabetes: part 1, pathogenesis. J Feline Med Surg. 1999 Sep
- Martin G, Rand J. Current understanding of feline diabetes: part 2, treatment. J Feline Med Surg. 2000 Mar
- Michiels L et al. Treatment of 46 cats with porcine lente insulin--a prospective, multicentre study. J Feline Med Surg. 2008 Oct
- Martin GJ, Rand JS. 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. J Feline Med Surg. 2001 Mar
- Martin GJ, Rand JS. Control of diabetes mellitus in cats with porcine insulin zinc suspension. Vet Rec. 2007 Jul 21
Websites
- Feline Diabetes, Cornell University, College of Veterinary Medicine
- http://www.felinediabetes.com/: the Original Internet Guide to Feline Diabetes
- Feline Diabetes and Diet: The High Carbohydrate Culprit, Lisa A. Pierson, DVM
