Veterinary Medicine - June 2008 - (Page c15)

Monitoring diabetes mellitus in diabetic cats the results of urine glucose testing.5,6,7 Serum fructosamine. Fructosamine is a glycosylated serum protein and a more speci c indicator of pancreatic endocrine activity than glucose. The reaction between glucose and this protein is irreversible; therefore, it represents the average blood glucose concentrations over a one- to three-week period.6,8 While reference ranges for serum fructosamine concentrations vary by laboratory, it is common that values less than 450 µmol/L represent moderate to good long-term glycemic control, while values less than 400 µmol/L indicate good to excellent control.4 You should evaluate relative changes in serum fructosamine concentrations, as well as absolute values. Because fasting and stress do not in uence the serum fructosamine concentrations, monitoring them is a viable option for evaluating excited cats.1 The hazard of adjusting the insulin dose based only on serum fructosamine concentrations (with or without urine glucose concentrations) is that both of these parameters will remain elevated in the face of a Somogyi e ect (i.e., hypoglycemia-induced rebound hyperglycemia). Elevated serum fructosamine may also be caused by concurrent illness, especially infection, in ammation, and pancreatitis; however, the most common cause is client error (i.e., the inability to correctly administer insulin).9 Some veterinarians prefer utilizing serum fructosamine concentrations, owner observations, and midday blood glucose concentrations, to utilizing blood glucose curves in established, stable diabetic cats.4 Glycosylated hemoglobin. Glycosylated hemoglobin is an indicator of the average blood glucose concentration that erythrocytes were exposed to in their lifetime.8 It is utilized in human medicine to monitor glycemic control over a three- to four-month period, but its use in cats is questionable because it is more di cult to measure and interpret.4 Persistently hyperglycemic cats The underlying reasons that some diabetic cats remain persistently hyperglycemic fall into three categories:1,9,10 1. Operator or case management error 2. Insulin resistance 3. The Somogyi e ect. Veterinarians must rst explore category one. Is the insulin outdated or has it been inappropriately handled? Is the client giving injections correctly—or at all? Is the client using the correct syringe? (The client’s insulin administration technique should be re-evaluated in-clinic at this time.) If the answers to these questions are satisfactory, then move to category two. The Somogyi e ect is due to insulin overdose. This can be tricky to di erentiate from insulin resistance, because blood glucose values can remain consistently high for two to three days after the hypoglycemic episodes. In the classic Somogyi curve, the time 0 blood glucose concentration is very high, the nadir blood glucose concentration is generally less than 50 mg/dl (2.7 µmol/ L), and the 12-hour blood glucose is very elevated, often higher than the time 0 measurement.11 If the Somogyi e ect is con rmed by the blood glucose curve, you can decrease the insulin dose to 0.3 to 0.5 U/kg for 10 to 14 days, and then gradually increase it while monitoring the blood glucose curve.2 Other di erential diagnoses of insulin resistance include concurrent disease or medications, such as corticosteroids or progestational substances.1,11,12,13 The most common causes of insulin resistance I nd are infections of the urinary tract, oral cavity, and skin. Hyperthyroidism, 15

Table of Contents Feed for the Digital Edition of Veterinary Medicine - June 2008

Veterinary Medicine - June 2008 Contents Leading Off Clinical Exposures Idea Exchange A Challenging Case: Conjunctival Lymphoma in a Cat Updates on Canine Hypoadrenocorticism Product Preview CE Form Advertiser Index Marketplace/Classifieds Mind Over Miller Clinical Edge - June 2008 Table of Contents Managing Diabetes Mellitus in Cats: What Makes it Work? Porcine Insulin Zinc Suspension in the Management of Feline Diabetes Mellitus Monitoring Diabetes Mellitus in Diabetic Cats Feline Diabetes Mellitus: Important Client Communication Points

Veterinary Medicine - June 2008

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