Pharmacology of OADs

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Note: there is a drug not mentioned in this list


  • Mentioned in NICE 2009 guideline for T2DM but not in 2015.
  • Insulin secretagogue, especially increases its secretion in response to glucose (first phase insulin release).
    – Used in patients with unpredictable meal time. 
    – Good to tackle postprandial hyperglycemia (mild increase in fasting glucose level but disproportionately high A1C)
  • Short duration of action (achieves peak plasma level in 1 hr & producing a rapid insulin-releasing effect that lasts for 3 hrs ) and hepatically excreted (T1/2 = 1 hr)
    – Can be used in renally-impaired patients
    – Lesser hypoglycemia (as it is short acting and increases insulin secretion IN RESPONSE to glucose, unlike sulfonylureas)

Rational of combination therapy

  • NICE suggests metformin + sulfonylurea or pioglitazone or DPP4i
  • Common threshold to initiate combination therapy is when A1C >8%.
  • With time, not only insulin resistance, there is loss of B-cell function as well (to abou 25% in 6 years).
  • Primary objective is to tackle the problems of insulin resistance + deficiency.
    – Metformin: insulin sensitizer
    – Pioglitazone: insulin sensitizer
    – Sulfonylurea: insulin secretagogue
    – DPP4i: GLP-1 based (increases insulin secretion)