Recently I visited a doctor concerned with my inability to lose weight. At the appointment I explained that I became pregnant at 127lbs, and was diagnosed with gestational diabetes at the start of my 3rd trimester. I was able to maintain my levels with a healthy diet and reduced exercise. After delivery I tested negative for diabetes, and slowly began to lose weight.. that is, until I received the Mirena IUD. Within a month I was back to my delivery weight of 161lbs (I'm 5'5"). After 13 months I had the Mirena removed. I've continued a healthy diet, and focus on exercise now more than ever. I'm now 18 months postpartum, I'm 27 and I still cannot get under 160lbs. The doctor prescribed me Phentermine, and told me that I needed to have my blood drawn for 'fasting insulin'. That my previous gestational diabetes could be the culprit of my inability to lose wight, and if the results from the blood work concluded this.. then there would be a different type of medication that would target this. What does this mean, and what type of medication is given for this?