Final answer:
A client with type 2 diabetes should monitor for muscle pain and dizziness as manifestations of lactic acidosis when taking metformin.
Step-by-step explanation:
When taking metformin, a client with type 2 diabetes should monitor for several adverse effects, including manifestations of lactic acidosis. Lactic acidosis is a rare but serious side effect of metformin and occurs when there is an accumulation of lactic acid in the body. Some of the findings that the client should watch for include muscle pain and dizziness. These can be potential signs of lactic acidosis and should be reported to the healthcare provider immediately for further evaluation and management.