- Current use of metformin, thiazolidinediones, glucagon-like peptide -1 receptor agonists, DPP-4 inhibitors, or weight loss medications (prescription or OTC) Patients must stop use of insulin sensitizers or antidiabetic medicines such as metformin for at least 4 weeks or thiazolidinediones, GLP1 agonists or DPPIV inhibitors for 8 weeks.