Participants were unable to be enrolled

Post-operative delirium happens when patients wake up from anesthesia. Patients experiencing post-operative delirium are very confused, not being able to think or function "normally". These patients are hard to take care of and they tend to have more dementia as they age compared to patients who don't experience post-operative delirium. Intranasal insulin has been shown to reverse confusion associated with Alzheimer's disease (humans) and AIDS (mice).

Intranasal insulin has been safely administered to 1092 patients in 38 different studies. There were no cases of clinically low blood sugar and a few cases of mild nasal irritation that happened also with salt water when the subjects received multiple intranasal doses.

No one has tried to reverse post-operative delirium with intranasal insulin. The delirium associated with Alzheimer's Disease and AIDS have very similar symptoms and what happens in the brain is very similar also.

The investigators intent is to administer intranasal insulin to patients exhibiting post-operative delirium in order to reverse the symptoms because the investigators think that the three disease states are closely related and intranasal insulin has had some success in reversing the delirium in the other two disease states.

Inclusion Criteria:

• All patients (>65 years of age) undergoing elective surgery using vapor anesthesia displaying post-operative delirium as defined by a CAM evaluation within time to PACU discharge post-surgery are eligible.
• Those patients 65 and older undergoing surgery using vapor anesthesia, who are consented but do not exhibit delirium and are not part of the study are still considered recruited subjects, but are not in the active study.

Exclusion Criteria:

• Patients with a history of severe dementia, anoxic brain injury, or neuromuscular disorders
• Non-English-speaking patients
• Planned use of drugs that effect plasma glucose concentration during the first four hours of surgery
• thiazolidinediones
• hormones which may affect plasma glucose or insulin
• contraceptive, diphenylhydantoin
• patients with allergy to insulin
• acromegaly
• Cushing's syndrome
• hyperthyroidism and pheochromocytoma
• renal impairment
• pregnant and lactating women
• base line blood glucose < 3.9 mmol/L

The investigational pharmacist will use randomization software to randomize numbers 1-30. Each number will be randomized to either active drug (regular insulin) or placebo (normal saline).The investigational pharmacist will have the randomization table should un-blinding be required.