Antagolin is not a drug, it is a herbal product. I have try to do some research on the ingredients, however, there is one ingredient that is not disclosed and it named insulin x if memory serves me correctly. So i there is no basis for me to recommend or discourage use of this product. I've been advising people to use glucostop which is a herbal product used in the treatment of diabetes. The ingredients however have shown to work in insulin resistance
There are some studies that show that fasting improves insulin sensitivity and others that say it induces insulin resistance. I would advise that during Ramadaan you eat low GI foods and lean meats, try to keep them as healthy as possible, try to stay away from the fried samoosas and cakes etc(but in moderation this is ok). Once Ramadaan is over, adopt a healthy diet with regular exercise as being pre-diabetic does not mean that you will develop diabetes. This can be avoided if you start taking better care of your health