Prevalence of abnormal hematocrit values (HCT) in diabetic is a phenomenon that is underestimated by physicians and diabetes nurse educators. HCT is generally considered to be quite stable in the range of 40-45% and blood glucose meters for patient self-testing are usually set to function properly with HCT concentration in this "normal range." However, a thorough investigation of the hematocrit distribution in an urban community has demonstrated a HCT-range of 30-50% in a healthy reference population. In community patients, the observed HCT ranged between 20% and 60%, and in hospital patients it was 10% to 70%. Patients in the intensive care units showed levels between 15% and 40%.1 In older patients also suffering from various diseases, these variations can even be more pronounced and may have an impact on the patient's prognosis, for example, in patients with kidney disease.2 In daily routine, changes in the hematocrit levels can be the result of lifestyle interventions (eg, smoking, prolonged exercise), can come with demographic conditions (eg, age), and can be induced by disease-and drug-related conditions (eg, hematological disorders, hypermenorrhea, pregnancy, or renal disease) and by environmental conditions (eg, stay in high mountains, seasonal variation). [3][4][5] Hematocrit interference has previously been identified as a source for inaccuracies of blood glucose meter readings in daily routine. 6,7 In meters employing static electrochemistry, Method: Venous heparinized blood was freshly drawn, immediately aliquoted, and manipulated to contain 3 different blood glucose concentrations (50-80 mg/dL, 150-180 mg/dL, and 350-400 mg/dL) and 5 different HCT levels (20-25%, 30-35%, 40-45%, 50-55%, and 60-65%). After careful oxygenation to normal blood oxygen pressure, each of the 15 different samples was measured 8 times with 2 devices and 2 strip lots of each meter (32 measurements/meter/sample). YSI Stat 2300 served as laboratory reference method. Next to determination of the mean absolute relative deviation (MARD), stability to HCT influence was assumed, when less than 10% difference occurred between the highest and lowest mean glucose deviations in relation to HCT over all tested glucose ranges (HIF: hematocrit interference factor).