Here's one study link...
https://www.ncbi.nlm.nih.gov/pubmed/23444965
After a quick read, I think they were trying to demonstrate that it works as well as Metformin.
I take a lot of nutritional supplements. I'm wary of anything that 1) suppresses appetite or 2) blocks absorption - (if it's blocking absorption of carbohydrates, is it also blocking uptake of nutrients?). For the cost, I'd consider gifting your cousin the highest quality vitamin and mineral supplement available, preferably made from whole foods. And a quality D3 supplement. At minimum, she'd feel better and perhaps be better able to evaluate her options.
I'd also suggest referring her here to this forum and to DietDoctor.com to learn more about the low carbohydrate ketogenic diet. She'll find lots of support here.
Glad you reached out to us.