Metformin is an inexpensive medication that is FDA-approved to manage high blood sugar levels in type 2 diabetes patients, but it may also give some mild amount of weight loss, Rao says
Reg Pept 62(1):2327

Researchers theorize this may be because: GIP activation may counterbalance some GLP-1 effects on the gut Dose escalation schedule allows more gradual adaptation Different pharmacokinetic profile may produce less pronounced peaks Serious Side Effects (Both Medications): These are rare but require immediate medical attention: Pancreatitis: Severe abdominal pain that may radiate to the back Risk: Less than 1% with both medications Usually occurs in first few months of treatment Requires immediate discontinuation if suspected Gallbladder Problems: Gallstones, cholecystitis (gallbladder inflammation) Symptoms: Right upper abdominal pain, nausea, fever More common with rapid weight loss May require surgical intervention Kidney Problems: Dehydration from vomiting/diarrhea can affect kidney function Watch for decreased urination, swelling in legs Stay well-hydrated, especially during side effect periods Thyroid Tumors (Black Box Warning): Both medications carry warnings about thyroid C-cell tumors Based on rodent studies

Fatigue or headaches Rare but can occur in individuals sensitive to peptides affecting metabolic pathways
doi: 10.1007/s10549-011-1585-0 89 TanakaYIwayaCKawanamiTHamaguchiYHorikawaTShigeokaTet al
GLP-1-based therapies such as liraglutide, semaglutide, and tirzepatide are widely used to treat T2D and obesity