Unlike traditional fertility medications, Metformin has not been linked to an increase in pregnancies involving twins, triplets and other births of more than one child.

iStockphoto/Thinkstock

It's an increasingly common phenomenon: A drug that was originally synthesized for a specific purpose turns out to be effective in combating another problem. Examples include Viagra (an unsuccessful treatment for angina that succeeded as an erectile dysfunction drug) and Thalidomide, a disastrously ineffective medication for pregnancy-induced nausea that has been proven to fight bone marrow cancer [source: Brown]. Metformin can also be included in this list, but with one significant difference. Not only is it helpful in a secondary role, but it's wildly popular in treating the condition for which it was initially intended.

Metformin was developed in the 1950s as a treatment for diabetes [source: Diabetes Forecast]. Today it's the most popular drug on the market for people with Type 2 diabetes [source: Science Daily]. But by 2004, Metformin was receiving international acknowledgement as a worthwhile option for patients seeking a remedy for their infertility. The U.K.'s National Collaborating Centre for Women and Children's Health noted that the drug, when used in conjunction with other medications, improved the rate of pregnancy in women with specific infertility issues tied to ovaries containing multiple cysts [source: NCCWCH].

The common denominator between Type 2 diabetes, Metformin and infertility can be described in one word: insulin. Insulin carries blood sugar to the body's cells to create energy. Some people's bodies, however, produce too little insulin, or the cells in the body refuse to accept the sugar it's transporting [source: American Diabetes Association]. That can lead to a multitude of health issues. Women whose infertility is tied to polycystic (multiple cysts) ovarian syndrome often have issues with insulin resistance. That's where Metformin comes in.