AIM: Although postprandial hyperglycemia is recognized as an important target in type 2 diabetes treatment, information on the prevalence of postprandial hyperglycemia throughout the day is limited. Therefore, we assessed the prevalence of hyperglycemia throughout the day in type 2 diabetes patients and healthy controls under standardized dietary, but otherwise free-living conditions. METHODS: 60 male type 2 diabetes patients (HbA(1c) 7.5+/-0.1% [58+/-1mmol/mol]) and 24 age- and BMI-matched normal glucose tolerant controls were recruited to participate in a comparative study of daily glycemic control. During a 3-day experimental period, blood glucose concentrations throughout the day were assessed by continuous glucose monitoring. RESULTS: Type 2 diabetes patients experienced hyperglycemia (glucose concentrations >10mmol/L) 38+/-4% of the day. Even diabetes patients with an HbA(1c) level below 7.0% (53mmol/mol) experienced hyperglycemia for as much as 24+/-5% throughout the day. Hyperglycemia was negligible in the control group (3+/-1%). CONCLUSION: Hyperglycemia is highly prevalent throughout the day in type 2 diabetes patients, even in those patients with a HbA(1c) level well below 7.0% (53mmol/mol). Standard medical care with prescription of oral blood glucose lowering medication does not provide ample protection against postprandial hyperglycemia.