Measuring the hemoglobin A(1c) (HbA(1c)) is the standard-of-care method to assess long-term glycemic control of patients with diabetes, describing the average glycemic level. However, the HbA(1c) does not reflect acute fluctuations in glucose levels. Variability of glycemia probably has an impact on the development of diabetes-related late complications. A novel model presented in this article combines different summary measures derived from continuously recorded glucose profiles (including parameters describing glycemic variability) and the HbA(1c). The five parameters taking into account are the axes of a "glucose pentagon." Connecting the values of these parameters provided an enclosed area of a given size. For a patient with diabetes, these parameters and the connected area describe how his or her glycemia was during the monitoring period. The area of the glucose pentagon for a patient with diabetes, divided by the standard area of healthy subjects, yields a non-dimensional characteristic value defined as the glycemic risk parameter. It is assume that this risk parameter provides a more meaningful overall description of metabolic control than the HbA(1c) alone. In addition, it might also allow a better assessment of a patient's risk for developing diabetes-related late complications in comparison to the HbA(1c) alone. Of critical importance is, of course, that the clinical relevance of the glucose pentagon is verified in adequate long-term clinical studies.