Hi. I had Sitagliptin for 2 years and is just another of the Gliptin family. The only side effect was a headache on and off for 2 weeks. It works by suppressing an enzyme that in turn switches the pancreas islet cells off after a meal. The end result is more insulin. You are wrong to worry about Metformin as the SR (Slow Release) version gives very few problems to most people and does help those who are overweight. It's the vanilla version that causes issues. If you have excess weight I would think about going onto Metformin SR as excess weight indicates too much insulin around not too little? BTW the Gliptins have no effect once blood sugar is down to normal so won't do any harm anyway.
