It is dangerous to rely on commercial websites claiming miracle cures. According to one survey 80% of such sites provide doctored, inaccurate information to make money from innocent patients. Glucofast is not a medicine. It is neither been approved nor tested for its safety and efficacy.
For insulin resistance, the first line therpy is metformin sold under various trade names such as Glyciphage, Walaphage etc. Its daily dose ranges between 500 mg twice daily to 850 mg three times daily with meals.