After administering lispro at 0810, if a client appears pale and diaphoretic by 0915, what should be the nurse's priority intervention?

The priority intervention in this scenario is to measure the capillary blood glucose level. Following the administration of lispro, a rapid-acting insulin, observing symptoms such as pallor and diaphoresis suggests that the patient may be experiencing hypoglycemia. In order to accurately assess the situation and determine the appropriate response, it is essential to first verify the patient's blood glucose level. This will confirm whether the symptoms are indeed due to low blood sugar.

Monitoring blood glucose is crucial because it allows the healthcare provider to make informed decisions regarding treatment; for example, if the blood glucose is low, the nurse can then administer glucose or carbohydrates to rectify the hypoglycemic state. Acting based on symptoms alone can be risky, as other conditions may cause similar signs. Therefore, obtaining an accurate measurement of the blood glucose level is the foundational step in providing safe and effective care in this situation.