A client is prescribed metformin for type 2 diabetes. What is an important teaching point?

Metformin is the first-line oral medication for type 2 diabetes. Mechanism: decreases hepatic glucose production, increases peripheral insulin sensitivity. Key teaching points: (1) Take with meals to minimize GI side effects (nausea, diarrhea, abdominal discomfort — often improve over weeks); (2) Hold for 48 hours before and after iodinated contrast studies due to risk of lactic acidosis — restart only after kidney function is reassessed and confirmed stable; (3) Hold during acute illness, dehydration, surgery (situations that increase lactic acidosis risk); (4) Does NOT cause hypoglycemia when used alone (unlike sulfonylureas and insulin) because it doesn't increase insulin secretion; (5) Symptoms of lactic acidosis (rare but life-threatening): malaise, muscle pain, respiratory distress, abdominal pain, hypothermia — rare but serious complication; (6) Risk factors for lactic acidosis: renal impairment (most important), heart failure, liver disease, alcoholism, advanced age, contrast dye exposure; (7) Avoid excessive alcohol use; (8) Vitamin B12 levels should be monitored periodically — long-term use can cause deficiency. Generally well-tolerated and weight-neutral or weight-loss promoting.