Medicine & USMLE


Diabetes Drugs (Old)
  1. Insulin Preparations
  2. Metformin
  3. Glitazones / Thiazolidinediones
  4. First-Gen Sulfonylureas
  5. Second-Gen Sulfonylureas
  6. Meglitinides
  7. GLP-1 Analogs
  8. DPP-4 Inhibitors
  9. alpha-Glucosidase Inhibitors
  10. Pramlintide


Metformin is the first line therapeutic drug used for Type 2 Diabetes. A drug in the biguanide class, metformin controls blood sugar in several ways. These include decreasing hepatic gluconeogenesis, increasing glycolysis, and increasing peripheral glucose uptake and insulin sensitivity. Notably, metformin can increase production of lactate in the body, leading to lactic acidosis. This is particularly common in patients with impaired kidney function, which is why metformin is contraindicated in renal failure. Other side effects to note are GI upset and vitamin B12 deficiency.

Key Points

  • Metformin
    • Biguanide class of drugs
    • Mechanism
      • ↓ hepatic gluconeogenesis
        • via inhibition of mGPD (mitochondrial glycerophosphate dehydrogenase)
        • appears to inhibit complex 1 of ETC, suppressing ATP formation (less important mechanism)
      • May also
        • ↑ glycolysis
        • ↑ peripheral glucose uptake
          • AKA ↑ insulin sensitivity
    • Clinical use
      • First-line therapy in type II DM
    • Toxicity
      • GI upset
      • No hypoglycemia
        • Because no insulin
      • No weight gain
      • Lactic acidosis
        • Caution in renal insufficiency
          • You NEED to check creatinine
      • B12 deficiency