Metformin vs. Victoza

Metformin is an oral drug used to treat type 2 diabetes. It lowers blood glucose by increasing the body’s sensitivity to insulin. Metformin does not increase insulin concentration or cause hypoglycemia when used alone. It can reduce complications such as heart disease, blindness, and kidney disease. Metformin also treats polycystic ovaries and weight gain caused by psychoses medications.

Victoza (liraglutide) is used with diet and exercise to improve blood sugar control in adults with type 2 diabetes. It works like the hormone GLP-1 (7-37) to slow food digestion, prevent excess sugar production, and stimulate insulin production when blood sugar is high.

QUESTION

What are the side effects of metformin and Victoza?

Metformin

The most common side effects are:

These symptoms occur in one out of three patients and may discontinue therapy in one out of 20 patients. Side effects are dose-related and may decrease with dose reduction.

Metformin may also cause:

• weakness or lack of energy
• respiratory tract infections
• low levels of vitamin B-12
• low blood glucose (hyperglycemia)
• constipation
• indigestion
• muscle pain
• heartburn
• chills

A serious but rare side effect is lactic acidosis. It occurs in one out of 30,000 patients and is fatal in 50% of cases. Symptoms include:

• weakness
• trouble breathing
• abnormal heartbeats
• unusual muscle pain
• stomach discomfort
• light-headedness
• feeling cold

Patients at risk for lactic acidosis include those with:

• reduced kidney or liver function
• congestive heart failure
• severe acute illnesses
• dehydration

Victoza

• The most common side effects are:
• Nausea
• Vomiting
• Diarrhea
• Constipation
• Upper respiratory tract infection
• Headache
• Flu-like symptoms
• Dizziness
• Sinusitis
• Back pain
• Reactions at the injection site

What is the dosage of metformin vs. Victoza?

Metformin

• For treating adults with type 2 diabetes, metformin (immediate release) usually starts at 500 mg twice a day or 850 mg once daily. The dose increases gradually based on glucose levels, up to a maximum of 2550 mg daily in three divided doses.
• If extended tablets are used, the starting dose is 500 mg or 1000 mg daily with the evening meal. The dose can be increased by 500 mg weekly up to 2000 mg (except for Fortamet). Fortamet and Glumetza are modified release formulations of metformin.
• Pediatric patients 10-16 years of age start at 500 mg twice a day, up to a maximum of 2000 mg daily in divided doses.
• Children older than 17 years of age may receive 500 mg of extended-release tablets daily, up to a maximum of 2000 mg daily.
• Metformin is safe for patients with mild to moderate renal impairment. Renal function assessment is necessary before starting treatment and at least yearly.
• Metformin should not be used by patients with an estimated glomerular filtration rate (eGFR) below 30 mL/minute/1.73 m2. Starting metformin in patients with an eGFR between 30-45 mL/minute/1.73 m2 is not recommended.
• Metformin should be stopped before administering iodinated contrast in patients with an eGFR between 30 and 60 mL/minute/1.73 m2, a history of liver disease, alcoholism, heart failure, or intra-arterial iodinated contrast administration. Kidney function should be evaluated 48 hours after receiving contrast.

Victoza

• Victoza is injected under the skin of the abdomen, thigh, or upper arm.
• Initial dose is 0.6 mg daily for one week to build tolerance to stomach side effects.
• After one week, the dose is increased to 1.2 mg daily.
• The maximum dose is 1.8 mg daily.

What drugs interact with metformin or Victoza?

Metformin

• Cimetidine (Tagamet) can increase metformin blood levels by 40% and cause more side effects. Metformin should be stopped 48 hours before and after using iodinated contrast media (e.g., Ioversol).
• Thiazide diuretics, steroids, estrogens, and oral contraceptives may increase blood glucose and reduce metformin’s effect. Alcohol consumption increases the risk of lactic acidosis.

Victoza

• Victoza may reduce the absorption of orally taken drugs. It is advised to separate administration of Victoza and oral medications. Combining it with insulin or insulin release-stimulating drugs may increase the risk of low blood sugar.

Subscribe to MedicineNet’s Diabetes Newsletter

By clicking "Submit," I agree to the MedicineNet Terms and Conditions and Privacy Policy. I also agree to receive emails from MedicineNet and I understand that I may opt out of MedicineNet subscriptions at any time.

Are metformin and Victoza safe to use when pregnant or breastfeeding?

Metformin

• There are no adequate studies in pregnant women. Insulin is recommended for pregnant women with diabetes. Metformin is excreted into breast milk.

Victoza

• There are no adequate studies of Victoza in pregnant women. Insulin is recommended for pregnant women with diabetes. Its transfer into human breast milk is unknown.

Summary

Metformin and Victoza (liraglutide) are used to treat type 2 diabetes. Metformin also treats polycystic ovaries and weight gain caused by psychoses medications. Metformin is taken orally while Victoza is injected under the skin.