Definition

Transient or persistently increased serum glucose concentrations.

Pathophysiology

• Insulin resistance and pancreatic amyloidosis (type 2 DM in cats).
• Insulin resistance from endogenous hormones (growth hormone) or drugs (corticosteroids).
• Absolute or relative insulin deficiency (type 1 DM in dogs).
• Increased gluconeogenesis and increased glycogenolysis (epinephrine release from stress, type 2 DM).

Systems Affected

• Endocrine/Metabolic-insulin resistance, hepatic glycogenolysis.
• Nervous-severe hyperglycemia may cause CNS dehydration from increasing serum osmolality. Hind limb weakness and plantigrade stance from diabetic neuropathy in cats.
• Ophthalmic-persistent hyperglycemia can cause cataracts in dogs.
• Renal/Urologic-osmotic diuresis from blood glucose exceeding the renal threshold (higher in the cat than dog) causes polyuria with secondary polydipsia.

Signalment

Cat and dog of any age or bree

Signs

Causes

• Relative or absolute insulin deficiency-type 1 and type 2 DM.
• Insulin resistance-type 2 DM in cats, hyperadrenocorticism, pheochromocytoma, glucagonoma, hypersomatotropism, hyperthyroidism, high progesterone during diestrus (dogs), renal insufficiency, urinary tract infection.
• Physiologic-post-prandial fluctuation and stress (epinephrine-induced) in cats.
• Drugs-thiazide diuretics, morphine, dextrose-containing fluids, progestins (e.g., megestrol acetate), growth hormone, glucocorticoids, and ACTH.
• Regulation problems in treated diabetics-high carbohydrate diets (cats), insulin administration problems, insulin-induced hypoglycemic hyperglycemia (rare).
• Parenteral administration of nutritional solutions.
• Laboratory error.

Risk Factors

• Stress in cats
• Concurrent disease-hyperadrenocorticism, acromegaly, and acute pancreatitis
• Diabetogenic drugs-steroids, progestagens
• Dextrose-containing fluids

Differential Diagnosis

• Mild, transiently high blood glucose can be associated with stress.
• In patients with mild hyperglycemia and no history of polydipsia/polyuria, repeat blood glucose determination after 12-hour fast and perform serum fructosamine.

Laboratory Findings

CBC/Biochemistry/Urinalysis

• Hyperglycemia may be the only abnormal finding.
• CBC-may be normal; possible inflammatory leukogram in patients with sepsis.
• Urinalysis-may be normal; glucosuria, pyuria, bacteruria, and ketonuria.
• Fasting hyperglycemia plus glucosuria suggests DM.
• Lipemia in patients with low lipoprotein lipase (miniature schnauzers), hyperadrenocorticism, acute pancreatitis, and post-prandial blood sampling.
• High amylase and lipase activity suggests acute pancreatitis, especially in non-azotemic patients.
• Increased plasma lipase immunoreactivity in patients with acute pancreatitis.
• High liver enzyme activity may accompany fatty infiltration with diabetes.

Other Laboratory Tests

• Fructosamine-normal values rule-out diabetes as cause of hyperglycemia.
• ACTH stimulation or low-dose dexamethasone-suppression test to rule-out hyperadrenocorticism.

Imaging

N/A

Diet

• High-protein, low-carbohydrate diet in cats with diabetes mellitus.
• High soluble fiber, low-fat diet in dogs with diabetes mellitus.

Drug(s) Of Choice

• Insulin-regular (crystalline) insulin for diabetic ketoacidosis, Lente insulin (dogs).
• Insulin glargine or PZI insulin in cats with DM.
• Oral hypoglycemics such as glipizide (cats with type 2 DM).

Contraindications

• Diabetogenic drugs (e.g., glucocorticoids)
• Dextrose-containing fluids

Precautions

Avoid rapid and aggressive insulin therapy that lowers blood glucose abruptly and causes hypoglycemia or cerebral edema.

Alternative Drug(s)

Acarbose 12.5 mg PO q12h; intestinal starch blocker

Patient Monitoring

• For return of clinical signs of diabetes such as polyuria, polydipsia, and polyphagia.
• Blood glucose after discontinuing diabetogenic drugs.
• Glycosylated hemoglobin and fructosamine on an outpatient basis to monitor long-term glucose control.

Possible Complications

• High incidence of sepsis (and infection).
• Severe hyperglycemia may be associated with CNS depression and coma because of hyperosmolarity.

Associated Conditions

• Hyperosmolarity
• Uremia may be associated with hyperglycemia

Pregnancy/Fertility/Breeding

N/A

Synonyms

High blood sugar

See Also

• Diabetes Mellitus without Complications-Cats
• Diabetes Mellitus without Complications-Dogs
• Hyperosmolarity

Abbreviations

• ACTH = adrenocorticotropic hormone
• CNS = central nervous system
• DM = diabetes mellitus