There are 24 million people with diabetes mellitus (DM) in the United States. Over one-third of patients presenting for coronary angiography have known DM, and an additional 20% of patients without known DM present with hyperglycemia on the day of coronary angiography. Hyperglycemia in the setting of urgent and elective percutaneous coronary intervention (PCI) is associated with a 40% relative increase in long-term mortality regardless of diabetic status. Mechanisms linking periprocedural hyperglycemia to adverse outcomes are poorly understood and the effects of treatment are unknown. This is a pilot study aimed at determining the effectiveness, feasibility and safety of continuing long-acting hypoglycemic medications on the morning of coronary angiography. Since hyperglycemia may cause increased platelet reactivity, a secondary aim is to evaluate a possible mechanism of benefit of periprocedural glycemic control on platelet activity. Patients with DM on hypoglycemic medications undergoing coronary angiography will be randomized to either continue or hold their clinically-prescribed long-acting hypoglycemic medications on the day of procedure. Patients with and without DM will be randomized to either routine care or additional glycemic control with the Yale insulin infusion protocol for 6 hours post-PCI. The primary endpoint of this study will be mean blood glucose level at the time of arterial access in the hold versus continue groups. Secondary endpoints will be mean blood glucose level at 6 hours post-PCI in the Yale versus routine care groups and number of hypoglycemic events in the glycemic control versus no glycemic control groups. The exploratory analysis assessing the effect of glycemic control on platelet activity will guide further studies evaluating the translation of an individual's platelet phenotype to the clinical risk of increased long-term mortality following PCI. The outcomes for this study (glucose levels and platelet function) are all measured during the hospital stay which averages 1 day.

Inclusion Criteria:

• All patients undergoing coronary angiography at the Manhattan Campus of the VA NY Harbor Healthcare System

Exclusion Criteria:

• 1. Patients who do not or are unable to consent. 2. Patients participating in a competing study. 3. For platelet substudy, patients who took NSAIDs within 72 hours of blood collection or who are on cilostazol or dipyridamole as part of their routine medication regimen. 4. Patients with any other co-morbidities that would influence subject safety.