Metformin (Glucophage)


Metformin (Glucophage)

  • Metaformin is in the class of biguanide drugs and is used as 1st line of oral treatment of diabetes type 2 unless there is a contraindication (ADA First Life Treatment Evidence A)
  • Metformin is cost effective (cheap)
  • Reduces hepatic glucose production & intestinal absorption of glucose & increases peripheral glucose uptake
  • Reduces A1C 1-2%
  • Works by decreasing hepatic glucose production and intestinal absorption of glucose and increases peripheral glucose uptake
  • Has a slow onset
  • Can cause lactic acidosis in patients with severe renal impairment
  • Should be discontinued before radiographic studies with IV iodinated contrast and should not be restarted until 48 hours after the procedure
  • Should not be used in patients with renal insufficiency or patients prone to lactic acid production (liver disease, severe infections, ETOH abuse, severe heart failure & conditions that lead to hypoxia)
  • 500mg is a common starting dose & can be increased up to 1000mg BID
  • Improves the lipid profile & helps with weight loss
  • Reduces CV risks
  • Does not cause hypoglycemia
  • Lowers both fasting blood sugar and postprandial blood sugar in people with type 2 diabetes
  • Not to be used in pt with renal insufficiency
  • can cause a B12 deficiency
  • Improves lipid profile
  • Promotes weight loss
  • Very safe when combined with other diabetic drugs


Side effects

  • GI side effects: nausea and diarrhea (most common)
  • If patient has diarrhea, give XR bc helps stop diarrhea or Imodium (OTC)
  • MAJOR TOXICITY: lactic acidosis- in patients with ↑Cre & LFT”s
  • Abd pain, vitamin b12 deficiency


Do not use Metformin 

Active Hepatitis C

Heart Failure 

Binge drinking


Treatment in pre diabetes

  • Consider metformin for obese patients < 60 years old who have both IFG (100-125) and IGT(140-199), plus any one of the following:
  • HBA1C 6.0 – 6.4%.
  • HTN
  • Low HDL cholesterol.
  • Elevated triglycerides.
  • Family history of DM in a 1st degree relative.
  • Monitor at least yearly.


Key Notes

Lifestyle modifications must be used with drug therapy
Welchol (colesevelam) is a good add on therapy with Metformin in a patient with elevated cholesterol LDL or in combo with diet and exercise.
Metformin may be used in patient with stable heart failure if they have normal renal function
Avoid metformin in patient with unstable heart failure


Hemoglobin A1C Goals for Type II DM & Pre-DM

Type II DM Type I DM Pre-DM Pregnant Women
A1C < 7% for adults A1C < 6% A1C 5.7 % - 6.4 % A1C < 6%
A1C < 8% for older


Edmunds, M. W., & Mayhew, M. S. (2014). Pharmacology for the primary care provider (4th ed.). St. Louis, MO: Elsevier Mosby.

Harvey, R. A., Clark, M. A., Finkel, R., Rey, J. A., & Whalen, K. (2012). Pharmacology (5th ed.). Baltimore, MD: Lippincott.