Insulin: Glargine

What is insulin glargine?

Insulin glargine is an injectable medication used in cats, dogs, ferrets, guinea pigs, and horses with diabetes mellitus. It is used to lower blood sugar levels and for long-term maintenance therapy for diabetes mellitus.

This medication is used off label (extra label) in pets. Many drugs are commonly prescribed for off-label use in veterinary medicine. “Off label” means the drug is being used in a way that has not been reviewed or approved by the U.S. Food and Drug Administration (FDA) or Health Canada. In these instances, follow your veterinarian’s directions and cautions carefully, as they may be significantly different from those on the label.

How do I give my pet insulin glargine?

• Insulin glargine comes in injectable form (vial and injection pen).
• Injections are given subcutaneously (under the skin).
• Use only U-100 syringes or the provided dosing pen with insulin glargine.
• This medication should be given at the same time every day.
• This medication should be given after a meal. If your pet is not eating, do not give this medication and consult your veterinarian for further instructions.
• Follow injection instructions provided by your veterinary team. Ensure the correct dose is given each time.
• Contact your veterinarian if you have difficulty drawing up the medication or giving injections.
• Give this medication to your pet for the entire time prescribed by your veterinarian; do not stop giving this medication suddenly.

What if I miss giving my pet the medication?

A single missed dose can cause temporary signs, but it is usually not life-threatening. Contact your veterinarian as soon as possible for advice on when to give your animal’s next dose. Never give two doses at once as this will cause an overdose. If you cannot reach your veterinarian and your animal is eating and acting normally, give your animal the usual dose at the next regularly scheduled time.

Are there any potential side effects?

Insulin glargine may cause the following side effects:

• Lumps or thickening of skin at injection site

Serious adverse reactions may occur. If any of the following signs develop, stop giving insulin glargine and contact your veterinarian immediately:

• Signs of low blood sugar, such as weakness, lack of energy, lethargy, stumbling or difficulty walking, behavior changes, muscle twitching, seizures (convulsions), or unresponsiveness
• An allergic reaction, such as irregular breathing, rash, fever, puffiness and swelling around the face

Drug sensitivities can develop over time with repeated exposure. Your pet may have no reaction after the first few doses but may develop a sensitivity later. It is important to watch for signs of an allergic reaction over the entire course of treatment and notify your veterinarian if you have any concerns.

Other side effects may occur. If you notice anything unusual, contact your veterinarian immediately. This long-acting insulin lasts for 12 to 16 hours.

Are there any risk factors for this medication?

DO NOT USE insulin glargine in:

• Pets that are allergic to any component
• Pets that are not eating
• Pets that show signs of low blood sugar or have confirmed low blood sugar (hypoglycemia)

If you suspect your pet’s blood sugar level is low, contact your veterinarian immediately. Hypoglycemia is a potentially fatal emergency.

Are there any drug interactions I should be aware of?

Certain medications should be USED WITH CAUTION when given with insulin glargine, including:

• Albuterol, terbutaline
• Certain medications used for sedation (e.g., acepromazine, dexmedetomidine, xylazine)
• Certain types of antibiotics (sulfonamides, fluoroquinolones)
• Clonidine
• Estrogens, progestins
• Fluoxetine, monoamine oxidase inhibitors (MAOIs)
• Medications used to treat heart conditions or control blood pressure (e.g., aspirin, beta blockers, angiotensin-converting enzyme inhibitors [ACEIs], calcium channel blockers, angiotensin II receptor blockers [ARBs], diuretics, disopyramide)
• Oral glycemic control medications (e.g., glipizide)
• Thyroid hormones

Be sure to tell your veterinarian about any medications (including vitamins, supplements, or herbal therapies) that your pet is taking before starting any new treatment.

Is any monitoring needed with this medication?

• When starting insulin glargine, your veterinarian will monitor baseline bloodwork and urinalysis to check organ function and for urinary tract infections.
• Close monitoring of blood sugar levels and overall health is required (e.g., appetite, energy, thirst, weight). Consult your veterinarian about recommended monitoring for your pet.
• At home, monitor for any side effects such as those noted above. If any occur, stop using the medication and contact your veterinarian.

How do I store insulin glargine?

• Unopened vials and pens: Refrigerate and do not freeze.
• Opened vials: Refrigerate or store at room temperature, away from direct sunlight and heat. 
• Opened pens: Store at room temperature, away from direct sunlight and heat.
• Discard all opened medication 28 days after first use, as outlined on the manufacturer’s label. Some veterinarians may recommend storing them in the refrigerator and using for longer than 28 days. Follow your veterinarian’s directions.
• Discard any medication that becomes cloudy or discolored.
• Follow your veterinarian’s recommendations on disposal of used sharps.
• Keep medication out of reach of children and pets.

What should I do in case of emergency?

If you suspect an overdose or an adverse reaction to the medication, call your veterinary office immediately. If they are not available, follow their directions in contacting an emergency facility. Be prepared to provide information about the product and your pet's weight and symptoms. Report any adverse effects to the FDA or Health Canada.