Metformin vs. Lantus

Metformin is an oral medication for treating type 2 diabetes. It increases sensitivity to insulin, reducing blood glucose levels. Metformin does not cause low blood glucose levels when used alone. It can reduce complications such as heart disease, blindness, and kidney disease. Metformin also treats polycystic ovaries and weight gain due to medications for psychoses.

Lantus is a man-made injectable long-acting insulin for regulating glucose levels in type 1 and type 2 diabetes. Lantus works like natural insulin, but its effect lasts longer. It promotes movement of sugar from blood into body tissues and stops sugar production in the liver.

QUESTION

What are the side effects of metformin and Lantus?

Metformin

The most common side effects of metformin are:

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

A serious but rare side effect of metformin is lactic acidosis. Lactic acidosis occurs in one out of every 30,000 patients and can be fatal. Symptoms include weakness, trouble breathing, abnormal heartbeats, unusual muscle pain, stomach discomfort, light-headedness, and feeling cold. Patients at risk for lactic acidosis include those with reduced kidney or liver function, congestive heart failure, severe acute illnesses, and dehydration.

Lantus

Common side effects of Lantus are:

• decreased blood sugar and injection site pain,
• water retention in the joints, and
• weight gain.

Local allergic reactions may occur at the injection sites. Long-term use of Lantus can lead to thickening of fat tissues at the injection site. Severe allergic reactions include swelling under the skin, very low blood pressure, and bronchospasm.

What is the dosage of metformin vs. Lantus?

Metformin

• For treating type 2 diabetes in adults, the starting dose is 500 mg twice a day or 850 mg once daily. The dose can be increased gradually as tolerated up to a maximum daily dose of 2550 mg.
• If extended-release tablets are used, the starting dose is 500 mg or 1000 mg daily with the evening meal. The dose can be increased gradually up to a maximum dose of 2000 mg.
• For pediatric patients 10-16 years of age, the starting dose is 500 mg twice a day. The dose can be increased gradually up to a maximum dose of 2000 mg.
• Children older than 17 years of age may receive 500 mg of extended-release tablets daily up to a maximum dose of 2000 mg daily.
• Metformin can be used in patients with mild to moderate renal impairment.
• Metformin should not be used in patients with an estimated glomerular filtration rate (eGFR) below 30 mL/minute/1.73 m2 and caution is advised in patients with an eGFR between 30-45 mL/minute/1.73 m2.
• Metformin use should be stopped in certain situations such as before and after receiving iodinated contrast.

Lantus

• The starting dose of Lantus should be individualized based on the type of diabetes and the patient’s insulin-naïve status.
• Lantus should be administered subcutaneously once daily at the same time every day. Injection sites should be rotated.
• Converting from other insulin therapies may require adjustment of timing and dose of Lantus.
• Glucose levels should be closely monitored during and after the conversion to Lantus.

What drugs interact with metformin and Lantus?

Metformin

• Cimetidine (Tagamet) can increase the amount of metformin in the blood, potentially increasing side effects.
• Iodinated contrast media may reduce kidney function and increase concentrations of metformin in the blood.
• Thiazide diuretics, steroids, estrogens, and oral contraceptives may increase blood glucose and reduce the effect of metformin.
• Alcohol consumption increases the risk of lactic acidosis with metformin use.

Lantus

Some drugs can decrease the blood sugar-lowering effect of Lantus:

• Corticosteroids, niacin, isoniazid, diuretics, estrogens, progesterone in oral contraceptives, and albuterol.

Are metformin or Lantus safe to use while pregnant or breastfeeding?

Metformin

• Insulin is the recommended treatment for pregnant women with diabetes.
• Metformin can be excreted into breast milk and should not be used by nursing mothers.

Lantus

• Safe and effective use of Lantus is not established for pregnant females.
• It is not known whether Lantus enters breast milk, so caution is advised in breastfeeding females.

Summary

Metformin and Lantus are used to treat diabetes. Metformin is for type 2 diabetes, while Lantus can be used for both type 1 and type 2 diabetes. Metformin also treats polycystic ovaries and weight gain due to medications for psychoses.