Final answer:
The nurse should report a serum potassium level of 3.0 mEq/L to the provider.
Step-by-step explanation:
The nurse should report a serum potassium level of 3.0 mEq/L to the provider. The normal range for serum potassium is 3.5-5.0 mEq/L. A potassium level of 3.0 mEq/L is below the normal range, indicating hypokalemia. Hypokalemia can be a serious complication for a client with diabetes mellitus and DKA, and it can lead to cardiac dysrhythmias. Therefore, it is important for the nurse to notify the provider so that appropriate interventions can be implemented to address the low potassium level.