一位第二型糖尿病病人使用二甲雙胍（Metformin）。護理師應將下列何種臨床表現視為需立即回報的高優先級副作用？
A client with type 2 diabetes is prescribed metformin. Which clinical manifestation should the nurse identify as a high-priority side effect to report immediately?
- AMetallic taste in the mouth口中金屬味
- BMild diarrhea after meals餐後輕微腹瀉
- CNausea and abdominal discomfort噁心與腹部不適
- DMuscle pain and lethargy✓ 正解肌肉疼痛與嗜睡
Metformin 罕見但致命的副作用為「乳酸中毒」（lactic acidosis）。早期徵兆包含不明原因的肌肉疼痛、無力與嗜睡（lethargy），是需立即回報的高優先副作用，可能伴隨腎功能異常或脫水。其他選項（金屬味、噁心腹脹、輕微腹瀉）為 metformin 常見且通常自限的腸胃道副作用，雖會影響服藥順從性，但不屬危及生命之徵兆。
Metformin's rare but lethal adverse effect is lactic acidosis. Early signs include unexplained muscle pain, weakness, and lethargy and represent a high-priority adverse effect that must be reported immediately; they may be accompanied by renal dysfunction or dehydration. The other options (metallic taste, nausea and bloating, mild diarrhea) are common, generally self-limited gastrointestinal side effects of metformin; although they may affect adherence, they are not life-threatening signs.