How long has metformin been in use to treat type 2 diabetes?

Metformin was approved for use in the United States by the Food and Drug Administration (FDA) to improve glycemic control in 1995.^1-4

However, the use of metformin dates back much farther. Dimethylbiguanide, the chemical compound of metformin, the was first described in literature in 1922.⁵ Its sugar-lowering effects were published in 1929, but it was eschewed in favor of more effective treatments.⁶ Metformin was briefly used as an antiviral treatment for influenza in the 1950s.⁷

Metformin has been available for use in the United Kingdom (UK) since the 1960s and in Canada since the 1970s.^8,9

References:

1. Glucophage (metformin hydrochloride) tablets, for oral use & Glucophage XR (metformin hydrochloride) extended-release tablets, for oral use. [Package insert]. Princeton, NJ: Bristol-Myers Squibb Company; 2018.
2. Riomet (metformin hydrochloride) oral solution. [Package insert]. Cranbury, NJ: Sun Pharmaceutical Industries; 2018.
3. Riomet ER (metformin hydrochloride for extended-release oral suspension). [Package insert]. Cranbury, NJ: Sun Pharmaceutical Industries; 2019.
4. Glumetza (metformin hydrochloride) extended-release tablets, for oral use. [Package insert]. Bridgewater, NJ: Valeant Pharmaceuticals; 2018.
5. Werner E, Bell J. The preparation of methylguanidine, and of ββ-dimethylguanidine by the interaction of dicyanodiamide, and methylammonium and dimethylammonium chlorides respectively Journal of Chemical Society, Transactions. 1922;121:1790-1794.
6. Slotta K, Tschesche R. Über Biguanide, II: Die blutzucker-senkende Wirkung der Biguanide. Berichte der Deutschen Chemischen Gesellschaft 1929;62(6):1398-1405.
7. Garcia EY. Flumamine, a new synthetic analgesic and anti-flu drug. J Philipp Med Assoc. Jul 1950;26(7):287-93.
8. Clarke BF, Duncan LJ. Comparison of chlorpropamide and metformin treatment on weight and blood-glucose response of uncontrolled obese diabetics. Lancet (London, England). Jan 20 1968;1(7534):123-6. doi:10.1016/s0140-6736(68)92726-8
9. Joncas F. Quatre annees d'etude clinique de la metformine chez 47 patients diabétiques. Union Med Can. 1972;101:65-70.