Who?
Metformin is a commonly recommended initial medication for patients with type 2 diabetes who have mild to moderately uncontrolled blood glucose. In addition, it is sometimes used to prevent diabetes in patients who are at risk of developing the disease (though it is not FDA approved for prediabetes). On average, most patients find that their HbA1c levels drop by as much as 1.5% on this medication. It can also be taken with insulin.
What?
Oral tablet
Metformin is manufactured under several different brand names. The most common ones are:
Where?
Metformin primarily reduces the liver’s ability to release glucose from its stores.
When?
Metformin is usually taken with meals, either once or twice a day depending on the brand. Available dosage of pills include 500 mg, 850 mg, and 1000 mg.
The treatment plan will differ for each patient, but a common starting regimen is listed below:
  • To avoid stomach upset, patients usually start with a very low dose (500 mg), taken with dinner.
  • After a few weeks, the dose may increase to 500 mg with breakfast and 500 mg with dinner.
  • A few weeks later, the dose may increase again to 500 mg with breakfast and 1 g with dinner.
  • If the patient has no side effects, the dose may increase to 1000 mg with breakfast and 1000 mg with dinner. This is usually the maximum dose.
Why?
  • Metformin is the treatment of choice for type 2 diabetes because it works well, is inexpensive, and it has been around for decades.
  • Patients may lose a few pounds of weight on metformin.
  • Metformin is very effective at controlling blood glucose and lowers A1c levels by as much as 1.5% at maximum doses.
  • By itself, metformin does not usually cause low blood glucose.
  • Side effects including diarrhea. However, a slow increase in doses or extended release preparations can often prevent this.
  • In rare cases, metformin can have a serious adverse side effect called lactic acidosis, where the body produces potentially dangerous levels of lactic acid. This condition is rare, and occurs more commonly in persons who are older or have from heart failure, history of heavy alcohol use, or advanced kidney disease.
  • To prevent serious kidney damage, patients generally should NOT take metformin for 24 hours before—or 48 hours after—receiving IV contrast for a CT scan.
  • Patients with mild-to-moderate liver or kidney problems may need to take reduced doses of metformin, and in severe cases, be discontinued from this medication.
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