How to assess the quality of glucose clamps? Evaluation of clamps performed with ClampArt, a novel automated clamp device

Abstract

Background: There are no widely accepted parameters to assess the quality of glucose clamps. Thus, we selected different parameters describing clamp quality. These parameters were then evaluated in glucose clamps carried out with ClampArt, a novel CE-marked, state-of-the-art fully automated glucose clamp device employing continuous blood glucose (BG) measurements and minute-by-minute adaptations of glucose infusion rate (GIR). Methods: Thirty-nine glucose clamps were performed in 10 healthy and 29 subjects with type 1 diabetes (T1DM) (total duration 583 h). ClampArt-based BG measurements were compared with those obtained with a laboratory reference method. Clamp quality was assessed by 5 parameters: (1) difference (mg/dl) of all paired BG measurements of ClampArt versus reference method ("trueness"), (2) coefficient of variation (CV, %) of ClampArt's BG measurements at target clamp level ("precision"), (3) mean absolute relative difference (MARD, %) at target clamp level ("accuracy"), (4) difference (mg/dl) between ClampArt and target BG ("control deviation"), and (5) percentage operational time ("utility"). Results: ClampArt-based BG measurements showed a trueness of 1.2 ± 2.5 mg/dl. CV and MARD at target BG were 5.5 ± 2.1% and 5.3 ± 2.3%, respectively. There were only small deviations from target level (1.2 ± 1.6 mg/dl). Operational time was as high as 95.4% ± 4.1% (means ± SD). Conclusions: The selected parameters seem to be adequate to characterize clamp quality. The novel, fully automated clamp device ClampArt achieves high clamp quality, which in future trials should be compared with other (automated and manual) clamp methods.