** Thanks for contacting with your health concern 1. Without being able to examine you directly, I m of the following opinion keeping in mind your age and drug history: i. As you are diabetic and on metformin do remember that nausea, burping/ flatulence, indigestion [which you are experiencing] are documented side effects of the drug. ii. vitamin B12 deficiency [intrinsic factor] level also decrease as the age progress and Metformin also causes malabsorption of Vitamin B12 thus they are more prone to atrophic gastritis. [check with Vit. B12 level] iii. One major effect of Metformin is lactic acidosis [LA], which can occur in presence of renal failure and alcoholism. [as you are in advance age which causes the renal function to decline thus check with kidney function test], since LA can cause nausea. [check with lactic acid test] 2. other factors which one has to keep in mind are: i. As the age progresses people tend to produce less acid [HCl] called as hypochlorhydria resulting in impaired/slower digestion. [and veggies are most affected since vegetarian diet are low in protein which can result in decreased production of HCl] ii. Lactose intolerance. 3. So it is best to put you on a dietary regime which is free from causing stomach upset/burping, like - Lactose-free product like soy milk, lactose-free milk, potato, rice, barley, margarine without butter/milk, fruit and vegetable juice, plain herbs and spice, jellies, jams - maintain a diet with low glycemic index/low fat. - eat smaller meals regularly and chew food thoroughly. - take a multivitamin which includes B3 and B12. . increase intake of fiber and omega 3 fatty acids PS. It could be IBS [irritable bowel syndrome] so consult call your doctor or a Gastroenterologist for necessary examination and investigation, since it can be symptoms of underlying illness or infection which require medical intervention.