Accuracy of two continuous glucose monitoring systems: a head-to-head comparison under clinical research centre and daily life conditions.

AIMS: To assess the accuracy and reliability of the two most widely used continuous glucose monitoring (CGM) systems. METHODS: We studied the Dexcom®G4 Platinum (DG4P; Dexcom, San Diego, CA, USA) and Medtronic Paradigm Veo Enlite system (ENL; Medtronic, Northridge, CA, USA) CGM systems, in 24 patients with type 1 diabetes. The CGM systems were tested during 6-day home use and a nested 6-h clinical research centre (CRC) visit. During the CRC visit, frequent venous blood glucose samples were used as reference while patients received a meal with an increased insulin bolus to induce an aggravated postprandial glucose nadir. At home, patients performed at least six reference capillary blood measurements per day. A Wilcoxon signed-rank test was performed using all data points ≥15 min apart. RESULTS: The overall mean absolute relative difference (MARD) value [standard deviation (s.d.)] measured at the CRC was 13.6 (11.0)% for the DG4P and 16.6 (13.5)% for the ENL [p < 0.0002, confidence interval of difference (CI Δ) 1.7-4.3%, n = 530]. The overall MARD assessed at home was 12.2 (12.0)% for the DG4P and 19.9 (20.5)% for the ENL (p < 0.0001, CI Δ = 5.8-8.7%, n = 839). During the CRC visit, the MARD in the hypoglycaemic range [≤3.9 mmol/l (70 mg/dl)], was 17.6 (12.2)% for the DG4P and 24.6 (18.8)% for the ENL (p = 0.005, CI Δ 3.1-10.7%, n = 117). Both sensors showed higher MARD values during hypoglycaemia than during euglycaemia [3.9-10 mmol/l (70-180 mg/dl)]: for the DG4P 17.6 versus 13.0% and for the ENL 24.6 versus 14.2%. CONCLUSIONS: During circumstances of intended use, including both a CRC and home phase, the ENL was noticeably less accurate than the DG4P sensor. Both sensors showed lower accuracy in the hypoglycaemic range. The DG4P was less affected by this negative effect of hypoglycaemia on sensor accuracy than was the ENL.

Dosing accuracy of insulin pens versus conventional syringes and vials.

Pen injection devices have acquired a pivotal role in insulin delivery, surpassing the use of conventional insulin syringes in many parts of the world. In this review we sought to determine differences in dosing accuracy between insulin pens and conventional syringes and vials, also touching on patient preference. We aggregated relevant literature found by searching the PubMed database, identifying seven relevant articles. There was consensus that pens are more accurate, especially at doses below 5 insulin units (IU). The literature also showed that pens tend to underdose when compared to syringes, but do this with a high degree of consistency. One study assessed influence on glycemic control, and whereas no significant difference was found with respect to hemoglobin A1c, fasting glucose levels decreased significantly more in pen users versus syringe users (-57 +/- 14 vs. 1 +/- 13 mg/dL, P = 0.003). The same study demonstrated that pens improved health-related quality of life compared to syringes and vials. We conclude that, regarding accuracy, there is sufficient evidence to recommend the use of insulin pens when delivering doses below 5 IU. For insulin doses above 5 IU there is no clear benefit for the pen in terms of accuracy.