Both Metformin and Insulin are antidiabetic drugs used to treat hyperglycemia in patients with diabetes. Metformin is used to treat insulin-independent diabetes (type 2 diabetes), while Insulin is used to manage insulin-dependent diabetes (type 1 diabetes). It may, however, also be used in the management of type 2 diabetes. Metformin is an oral antidiabetic drug, while Insulin is only available as an injection in managing hyperglycemia. Whereas Insulin is used in the treatment of diabetes, metformin may also be used to treat polycystic ovarian syndrome and weight gain.
Metformin belongs to a group of antidiabetics called biguanides. It is the first-choice drug in the management of type 2 diabetes. It decreases the gluconeogenesis process in the liver, causing glucose production (Corcoran & Jacobs, 2018). It also increases peripheral glucose utilization and uptake, therefore, increasing insulin sensitivity. It also decreases the gastrointestinal absorption of glucose. The resultant effect is a reduction in the plasma glucose level and the control of hyperglycemia. The adverse side effects of using metformin include lactic acidosis, unpleasant metallic taste, hypoglycemia, nausea, vomiting, reduced vitamin B12 levels, diarrhea, and bloating (Katzung, 2018).
After oral administration, 50-60% metformin is bioavailable for absorption (F.A. Davis Company, 2015). Food reduces the absorption of metformin. After an oral administration of the drug, the distribution volume is about 654 ± 358 L (Drug Bank, 2017). It binds negligibly to proteins. Metformin does not undergo any hepatic metabolism and is excreted unaltered in the urine. It has an elimination half-life of around 17.6 hours (F.A. Davis Company, 2015). Metformin is excreted through the kidneys.
Insulin acts by promoting the uptake of amino acid and glucose into adipose and muscle tissues. Its anabolic effects stimulate the synthesis of protein, glycogen, and fatty acid from glucose. Additionally, it inhibits gluconeogenesis in the liver (Dave & Preuss, 2020). The effect is the reduction in blood glucose levels and thus the control of hyperglycemia. Insulin’s side effects include lipodystrophy, hypoglycemia, swelling, edema, pruritus at the injection site, and an anaphylactic reaction.
Human Insulin is rapidly absorbed after subcutaneous injection with a peak plasma concentration between 1.5-2.5 hours (Drug Bank, 2019). The glucose reducing action begins approximately 30 minutes post-injection. Insulin is distributed in the body, similarly to endogenous Insulin. It is metabolized in the muscle, spleen, liver, and kidney, just like the regular Insulin. Insulin is cleared from the system through the kidneys. The half-life of Insulin is about 30minutes to an hour.
Metformin for a dosage of 500mg twice daily dosage costs between 50-70$ for 180 tablets (GoodRx, 2020). The average price of Insulin is between 150-180$ for 100 units of Insulin. These drugs can be gotten in different areas, and the generic forms of the drugs are cheaper than the original forms. Metformin was first discovered in the year 1922. It was then studied in humans by a French scientist Jean Sterne in the 1950s (Bailey, 2017). The drug was introduced for use in diabetes treatment in France in 1957 and in 1995 in the USA. The medical use of Insulin began in the 1900s after a 14-year-old boy with diabetes was successfully managed, resulting in the prolongation of his life. It has since been used to treat diabetes. Both metformin and Insulin have good safety profiles and can be used to treat diabetes without so many adverse side effects. They pose little to no effect for the unborn babies; therefore, they are safe to use in pregnancy.
In my clinical experience, I have experienced the utilization of both drugs in the management of diabetes. In one case, a patient with type 2 diabetes who was obese was started on metformin 500m BD dose as the first-line treatment. However, there was poor glucose control due to non-compliance. The patient’s HBA1c was 9%. The patient had constant high sugars during the admission period and had to be converted from the oral antidiabetic to the injectible, and Insulin was initiated. The patient underwent proper nutritional counseling and was discharged on subcutaneous Mixtard injections to help control his sugars.
In summary, both metformin and Insulin are antidiabetic drugs but with different mechanisms of action and different uses in the management of diabetes. Metformin is mostly used as an oral anti-glycemic drug in the management of type 2 diabetes. At the same time, Insulin is primarily used in type 1 diabetes but may also be used in type 2 diabetes. The two drugs, when effectively used, can help patients achieve proper glycemic control. Both drugs have good side effect profiles and can be used without adverse side effects. They are easily available and cost-friendly and may only be obtained through a prescription.
References
Bailey, C. J. (2017, September 1). Metformin: Historical Overview. Retrieved from Diabetologia website: https://pubmed.ncbi.nlm.nih.gov/28776081/
Corcoran, C., & Jacobs, T. F. (2018, October 27). Metformin. Retrieved from Nih.gov website: https://www.ncbi.nlm.nih.gov/books/NBK518983/
Dave, H. D., & Preuss, C. V. (2020). Human Insulin. Retrieved from PubMed website: https://www.ncbi.nlm.nih.gov/books/NBK545190/
Drug Bank. (2017, October 17). Metformin. Retrieved from go.drugbank.com website: https://go.drugbank.com/drugs/DB00331
Drug Bank. (2019). Insulin human. Retrieved from go.drugbank.com website: https://go.drugbank.com/drugs/DB00030
F.A. Davis Company. (2015). metFORMIN (met-for-min). Retrieved from https://davisplus.fadavis.com/3976/meddeck/pdf/metformin.pdf
GoodRx. (2020). Metformin ER (Glucophage XR) Prices, Coupons & Savings Tips. Retrieved October 18, 2020, from GoodRx website: https://www.goodrx.com/metformin-er-glucophage-xr
Katzung, B. G. (2018). Basic & clinical pharmacology (14th ed.). New York I 11 Pozostałych: Mcgraw-Hill Education, Copyright.