The purpose of this study is to compare the safety and efficacy of intravenous (IV) administration of FDA approved regular human insulin and subcutaneous (SC) administration of humalog, a rapid-acting insulin analog (a synthetic insulin), for correction of hyperglycemia (high blood sugar) during the immediate preoperative period in patients with diabetes having outpatient surgery at the Emory Ambulatory Surgical Center (ASC).

In this randomized controlled clinical trial patients with diabetes will be administered corrective doses of IV regular insulin or SC humalog for preoperative hyperglycemia to determine whether SC humalog results in improved intra and post-operative blood sugar control.The most common current practice at Emory University in the ambulatory surgical setting is IV administration of regular insulin for treatment of pre-operative hyperglycemia. Subjects will not be paid for their participation and will be assured of treatment for their hyperglycemia regardless of study participation.

Investigators plan to randomize a total of 200 male and female subjects with type 1 and type 2 diabetes,having an out patient surgical procedure, meeting inclusion criteria to receive corrective doses of IV regular insulin (Group I) or SC humalog insulin (Group II). The dosing formula is per Emory University Outpatient Surgical Center protocol for treating hyperglycemia and is the same for both groups. All patients with diabetes will undergo a blood sugar measurement upon arrival to the ASC using the Accuchek blood glucose meter. An admission blood sugar of >180 in a patient with diabetes qualifies the patient for study screening. Subjects will be approached after confirmation of eligibility for the study. Randomization, then treatment, will occur immediately following written informed consent. Demographic data will be recorded.A medical history with detailed history of diabetes will be obtained and surgical and anesthesia details and length of stay recorded. Blood sugar levels will be checked hourly until the patient is ready for discharge. Subsequent treatment will follow the hyperglycemia protocol. All blood sugar results and doses of insulin will be recorded. The subject's participation will end at the time of discharge from the Ambulatory Surgical Center.

Inclusion Criteria:

• Male or female patients between the ages of 18 and 80 years with type 1 and type 2 diabetes
• patients undergoing ambulatory surgery
• a known history of diabetes for > 3 months treated with diet, oral antidiabetic agents and/or insulin therapy
• subjects with an admission/randomization Blood glucose> 180 and < 400 mg/dl
• Patients willing and able to provide informed consent

Exclusion Criteria:

• Age < 18 or > 80
• Subjects with increased blood glucose concentration, but without a history of diabetes (stress hyperglycemia)
• Patients on an insulin pump
• Patients with a history of clinically significant hepatic disease (cirrhosis, jaundice, end-stage liver disease, portal hypertension) and end- stage renal disease
• Current or recent (within 3 months) treatment with oral or injectable corticosteroid, parenteral nutrition and immunosuppressive treatment
• Mental condition rendering the subject unable to understand the nature, scope and possible consequences of the study
• Female subjects whom are pregnant or breast-feeding at time of qualifying outpatient procedure