A visit to a physician's office may provoke an increase in blood pressure. Stress is also a well-known glycemic aggravation, and managing diabetes with ongoing stress is often difficult. Two patients with diabetes mellitus in whom anxiety and stress contributed to transient hyperglycemia that impacted adversely on their diabetes management are presented. "White coat" hyperglycemia should be suspected when the clinical glucose levels are higher than the glucose levels measured by the patient at home and the clinical glycohemoglobin levels. The recognition of white coat hyperglycemia is especially important with the recent findings that intensive therapy effectively delays the onset and slows the progression of diabetic complications in patients with insulin-dependent diabetes mellitus. Failure to appreciate white coat hyperglycemia will increase the risk of hypoglycemic episodes, some of which may be severe and life threatening.