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nutrition and diabetes


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All Metformin Products Not Created Equal?

Female doctor placing pills in a medicine bottle.

Different metformin products might affect blood glucose differently too.

Our clinical staff has recently received inquiries regarding the medication products that contain Metformin. As this is a very commonly used diabetes medication and there are various forms of available, I wanted to share the information with you.

Metformin was introduced in Europe in the 1950's and the Food and Drug Administration (FDA) approved its use in the U.S. in December 1994. In general, metformin products:

  • Decrease the amount of glucose released by the liver
  • Decrease intestinal absorption of glucose
  • Improve insulin sensitivity
  • Improve glucose utilization in skeletal muscle and adipose tissue.

The main differences in the various products, detailed below, involve the chemical coating of the products and their location of action. If you have questions about the metformin product you take, contact your physician or diabetes educator.

"Regular release" metformin manifests most of its actions in the "gut" or intestinal areas. Its usual peak action time in the plasma blood is approximately 2 hours and it is usually taken with food. Food can help increase its absorption. 

Fortamet is coated with a semi-permeable membrane so that it releases metformin at a slower, more constant rate than regular metformin. Its peak action time is approximately 6 hours. It should also be taken with food. As of September 2011, the 500mg strength is on back order and  the next expected release date is October 12,2011. The 1,000mg strength remains available.

Glumetza  uses “gastric retentive” technology that causes the tablets to remain in the stomach rather than progress to the gut/lower intestinal area. It delivers the metformin to the upper GI tract to enhance absorption over an extended period of time and its peak action is at approximately 8 hours. Glumetza must be administered immediately after a meal to maximize its therapeutic effect. After 15 minutes the tablet absorbs water from the gastric juices and expands in size allowing  for the slower digestion and release of the medication so that it stays in the bloodstream longer.

Of course, testing your blood sugar at various times of the day will help determine which/how the metformin products affect you, in particular. It is not recommended that the extended release versions of these meds be broken or crushed. 

It is very important to carry a list of all your medications, with their correct names, as there could be several formulations of them. It is also important to continue testing your blood glucose, at various times of the day, to help determine which medications may be appropriate and their particular effects on you.  Please share any concerns or questions with our staff.

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