You should seek the advice of your veterinarian if your pet is ill as only he or she can correctly advise on the diagnosis and recommend the treatment that is most appropriate for your pet.

The use of oral hypoglycemic drugs is limited to Type II (non-insulin dependent) diabetes mellitus. Recent studies suggest that some of these drugs may be beneficial in the management of Type II diabetes mellitus in cats

Oral hypoglycemic agents are widely used in human medicine for the management of non-insulin dependent diabetes mellitus (NIDDM) patients who can not be managed by diet alone. They should not be given to patients with insulin dependent diabetes mellitus (IDDM). Patients with long standing NIDDM often require insulin in addition to hypoglycemic drugs.

Dogs invariably develop Type 1 (insulin dependent) diabetes mellitus which can not be treated solely using oral hypoglycemic drugs. Cats on the other hand usually have Type II (non-insulin dependent) diabetes mellitus and recent studies suggest that some oral hypoglycemics may be of use in the management of these cases.(See also Diabetes Mellitus)

1. a-glucosidase inhibitors

These drugs (eg acarbose) reduce starch and disaccharide absorption from the brush border by inhibiting the action of the enzyme a-glucosidase and they reduce post-prandial hyperglycemia. Acarbose does not stimulate insulin release from the pancreas nor does it increase peripheral activity of insulin in tissues. So, acarbose does not cause hypoglycemia.

Acarbose is used in human medicine for  the treatment of patients with NIDDM and as an adjunct to insulin in IDDM. It is given to obese human patients which are in a pre-NIDDM state. However, it causes unacceptable side-effects including flatulence, bowel cramps and diarrhoea. In dogs it has been used at 25-100 mg twice daily by mouth and has been reported to improve control of hyperglycemia when given with insulin in some cases of diabetes mellitus. Unfortunately, dogs develop a dose-dependent diarrhoea.

In cats acarbose has been given at a dose of 12.5-25mg/cat with food. By itself it only reduces hyperglycemia to the range 250-300mg/dl but it is reported to work well when given with insulin. As in humans, flatulance, and loose stools have been reported to occur.

 

   2.    Biguanides

Like acarbose, these products (eg metformin) do not stimulate insulin secretion from the pancreas and so the risk of hypoglycemia is less than with the use of sulfonylureas. Metformin can be used by itself or in combination with sulfonylureas and it acts mainly by inhibiting gluconeogenesis in the liver, but also by delaying glucose absorption from the gastrointestinal tract and increasing glucose uptake by peripheral tissues.  It reduces LDL and VLDL cholesterol concentrations in the blood, whilst increasing HDL cholesterol. 

Metformin is not metabolised and is excreted via the kidneys. Side -effects include weight loss, gastrointestinal problems, reduced vitamin B₁₂ absorption and rarely, a potential  fatal lactic acidosis. It is contra-indicated in renal and hepatic insufficiency.

There are no reports of the use of these products in cats or dogs.

 

  3.     Sulfonylureas

The sulfonylureas (eg tolbutamide, glyburide and glipizide) have the following mechanisms of action :

• They stimulate insulin release from the b-cells of the pancreas
• They reduce glucagon concentrations in the blood
• They increase tissue receptor binding of insulin

These drugs are metabolised by the liver and excreted via the liver and kidneys, and they are contraindicated in renal and hepatic insufficiency. They are also contraindicated in pregnancy as they cross the placenta and can cause depletion of insulin from the fetal pancreas.

Sulfonylureas (glipizide) have been used in cats:

• In one study involving 20 cats with NIDDM a long term response was achieved in 55%
• In another study involving 50 cats with NIDDM a success rate of 38% was found. 
• About 15% of cats develop vomiting
• 10% develop signs of liver injury - including jaundice and increased serum liver enzymes within 4 weeks of treatment being started. 
• Hypoglycemia occurs in about 15% of the cats which respond to treatment. 
• Cats without significant side-effects can be treated for life.
• Glipizide loses efficacy (time varies from weeks to years) in about 10% of cats
• Glipizide dose : 2.5mg/cat twice daily with food. If no side-effects after 2 weeks increase dose to 5mg/cat twice daily.
• Monitor glucose tolerance and screen for evidence of liver damage. Stop treatment if side-effects occur.
• If get no clinical response after 12 weeks stop glipizide and start insulin.
• If get reduced clinical signs, no glycosuria and blood glucose concentrations of < 200mg/dl glipizide should be stopped. If hyperglycemia recurs it can be restarted at half the original dose rate.
• Normoglycemia can last for more than 12-14 months following a course of successful glipizide therapy.
• 3 monthly checks are advised.
• Glycosylated hemoglobin and fructosamine concentrations are good indicators of glycemic control.

  4.     Transition Metals

Vanadium and chromium are used as oral hypoglycemic agents. Studies in cats have shown :

• 0.2mg/kg/day oral vanadium (Vanadyl Fuel) decreased blood glucose concentrations and removed clinical signs in cats with early NIDDM.  Compared to a placebo controlled group the treated group gained weight, clinical signs resolved and serum fructosamine concentrations decreased.
• Chromium has also been used at 200mg/cat once daily by mouth.

  5.      Thiazolidinediones

These agents (eg troglitazone) increase peripheral tissue sensitivity to insulin, reverse insulin resistance and improve glucose and lipid homeostasis. They do not increase insulin secretion from the pancreas. 

Troglitazone has been used in cats (at a dose of 200mg/cat once daily) but there were no observed improvements in glucose concentration or in clinical signs.

If oral hypoglycemic drugs are to be used effectively in the management of Type II NIDDM in cats, they should be given to non-ketoacidotic cats with stable diabetes, mild signs and a  normal weight or slightly overweight body condition. Obese animals should be placed on a weight-reduction programme.

Updated October 2013