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Diabetes Mellitus, Uncomplicated

basics

definition :

Disorder of carbohydrate, fat, and protein metabolism caused by an absolute or relative insulin deficiency. Type I (insulin-dependent diabetes mellitus [DM]) is characterized by very low to absent insulin secretory ability. These patients die if not treated with insulin and are prone to ketoacidosis. Type II (noninsulin- dependent DM) is characterized by inadequate or delayed insulin secretion relative to the needs of the patient. Many of these patients live without exogenous insulin and are less prone to ketoacidosis.

Pathophysiology:

Insulin deficiency causes an impaired ability of tissues, especially muscle, adipose tissue, and liver, to utilize carbohydrates, fats, and proteins. Impaired glucose utilization and ongoing gluconeogenesis cause hyperglycemia. Glucosuria develops, causing osmotic diuresis, polyuria, and compensatory weight loss. Mobilization of free fatty acids to the liver causes both hepatic lipidosis and ketogenesis.

Systems Affected :

Genetics:

Familial associations in some breeds of dog

Incidence/Prevalence :

Prevalence in both dogs and cats varies between 1:400 and 1:500.

signalment :

Mean Age and Range :

Dogs--mean about 8 years; range, 4-14 years (excluding rare juvenile form)

Cats-- 75% are 8-13 years; range, 1-19 years

Predominant Sex:

signs :

causes :

risk factors :

diagnosis :

differential diagnosis :

CBC/Biochemistry/Urinalysis

other laboratory tests :

imaging :

other diagnostic procedures :

Liver biopsy (percutaneous)--indicated in some jaundiced patients

gross and histopathologic findings :

Usually no gross necropsy changes

Histopathologic findings may be normal or reveal vacuolar degeneration of the islets of Langerhans or low numbers of islet cells. Immunohistochemical staining is necessary to show low numbers of beta cells. In cats, amyloid deposits in the islets are usually seen.

treatment :

inpatient versus outpatient

Compensated dogs and cats can be managed as outpatients. They are alert, hydrated, and eating and drinking without vomiting. For management of decompensated patients, see Diabetes Mellitus, Ketoacidotic.

activity

Strenuous activity may lower insulin requirement. Consistent amount of activity each day is helpful.

diet

client education

Discuss daily feeding and medication schedule, home monitoring, signs of hypoglycemia and what to do, and when to call or visit veterinarian. Clients are encouraged to keep a chart of pertinent information about the pet, such as urine dipstick results, daily insulin dose, and weekly body weight.

surgical considerations

Intact females should have an ovariohysterectomy when stable. Progesterone secreted during diestrus makes management of DM difficult.

medications

drugs and fluids

Fluid therapy--see Diabetes Mellitus, Ketoacidotic

Insulin--treatment of choice for all dogs and most cats

Insulin mixtures add rapid bioavailability to longer duration insulins. The lente series can be mixed in any combination. NPH and regular insulin mixtures are commercially available. A combination of 25% regular and 75% ultralente can be used after it equilibrates in the vial for 24 hours. Most animals can be managed without insulin mixtures.

Species of origin of the insulin may affect pharmacokinetics. Beef, pork, beef/pork, and human recombinant insulin are options. Animal-origin insulins are being phased out. Keep the pet on the same type and species of insulin if possible. When changing from an animal origin to human recombinant insulin, lower the dosage and reregulate the animal.

Oral administration of hypoglycemic agent--glipizide is useful with dietary therapy in some cats with type II DM. The cat should have uncomplicated DM and no history of ketoacidosis. Initial dosage, 2.5 mg PO q12h. Monitoring is the same as for patients on insulin. If hyperglycemia is not controlled, 5 mg q12h may be tried. Potential side effects are hypoglycemia, hepatic enzyme alterations, icterus, and vomiting.

precautions

possible interactions

Many drugs (e.g., NSAIDs, sulfonamides, miconazole, chloramphenicol, monoamine oxidase inhibitors, and beta blockers) potentiate the effect of hypoglycemic agents given orally. Consult the product insert.

alternate drugs

Dietary therapy or oral administration of hypoglycemic agents or both can be tried if owners are unwilling or unable to give insulin. This is more successful in cats than dogs.

follow-up

patient monitoring

Glucose curve--the best method of monitoring. The owner feeds the pet, injects the insulin, and then brings the patient to the hospital for serial blood glucose testing every 1-2 hours, beginning about an hour after the injection. Animals receiving insulin q12h are followed for 12 hours, and those on insulin q24h are followed for 24 hours. The goal is to maintain blood glucose between 100 and 200 mg% for at least 20-22 hours per day in dogs, and between 100 and 300 mg% in cats. The curve is performed every few weeks until the disease is regulated, and then every few months or whenever a problem arises.

Urine glucose monitoring--urine is tested for glucose and ketones before the meal and insulin injection. To use this as a regulatory method, the pet must be allowed to have trace to 1/4% glucosuria to avoid hypoglycemia. Animals regulated by urine alone may be more hyperglycemic than ideal, and insulin overdose with rebound hyperglycemia is an inherent risk with this method. It is most useful to combine urine monitoring with intermittent glucose curves. Owners should seek veterinary attention if ketonuria is detected.

Clinical signs--owner can assess degree of PU/PD, appetite, and body weight. If these are normal, the disease is well regulated.

prevention/avoidance

Prevent or correct obesity. Avoid unnecessary use of glucocorticoids or megestrol acetate.

expected course and prognosis

Some cats recover but may relapse at a later time. Dogs have permanent disease. Prognosis with treatment is good. Most animals have a normal life span.

miscellaneous

Urinary tract infection

age related factors

Juvenile DM is rare and may be more difficult to manage.

pregnancy :

Diabetes mellitus can develop during pregnancy, in which case the pregnancy is difficult to maintain. Exogenous insulin administration may cause fetal oversize and dystocia. Insulin resistance develops, making hyperglycemia difficult to control. The pregnant bitch is prone to ketoacidosis. An emergency ovariohysterectomy may be necessary. Dogs with DM should not be used for breeding.

abbreviations :

references :

Nelson RW. Diabetes mellitus. In: Ettinger SJ, Feldman EC, eds. Textbook of veterinary internal medicine. Philadelphia: WB Saunders, 1995:1510-1537.

Wallace MS, Kirk CA. The diagnosis and treatment of insulin-dependent and non-insulin-dependent DM in the dog and the cat. Prob Vet Med 1990;2:573-590.

Author Melissa S. Wallace

Consulting Editor Rhett Nichols

The majority of the information in this page is has been taken from VetMedCenter.com. For further information about this useful source of informtion follow the link or look, on the internet, at www.vetmedcenter.com.