Table 5.
Comparisons between closed loop delivery of insulin and conventional insulin pump therapy based on plasma glucose concentrations after pooling results for two meal scenarios: eating in and eating out. Data are medians (interquartile ranges) unless stated otherwise
| Period and outcome | Insulin delivery system | Paired difference* (n=24) | P value | |
|---|---|---|---|---|
| Closed loop (n=24) | Insulin pump (n=24) | |||
| From start of closed loop delivery† | ||||
| Mean (SD) plasma glucose level at start (mmol/L) | 7.1 (2.8) | 7.7 (3.7) | −0.6 (4.2) | — |
| Mean (SD) overnight plasma glucose level (mmol/L) | 6.7 (1.1) | 6.8 (1.5) | −0.1 (1.1) | 0.84 |
| SD of overnight plasma glucose level (mmol/L) | 1.4 (1.1 to 1.8) | 2.0 (1.6 to 2.7) | −0.5 (−1.0 to −0.1) | 0.001 |
| Mean amplitude of glucose excursions (mmol/l) | 3.6 (2.4 to 4.0) | 5.0 (3.6 to 8.4) | −1.5 (−4.0 to 0.0) | 0.003 |
| Time plasma glucose level spent in target (%) | 76 (60 to 88) | 50 (32 to 70) | 22 (3 to 37) | <0.001 |
| Time spent at plasma glucose level (%): | ||||
| ≤3.5 mmol/L | 0 (0 to 4) | 4 (0 to 17) | −1 (−12 to 0) | 0.02 |
| ≤3.90 mmol/L | 3 (0 to 9) | 7 (0 to 25) | −3 (−20 to 0) | 0.04 |
| >8.0 mmol/L | 18 (2 to 36) | 30 (12 to 54) | −11 (−30 to 1) | 0.006 |
| Low blood glucose index | 1.0 (0.5 to 2.0) | 1.9 (0.5 to 4.5) | −0.9 (−3.0 to 0.1) | 0.01 |
| Insulin infusion (U/h) | 0.8 (0.6 to 1.0) | 0.8 (0.6 to 1.0) | 0.0 (−0.1 to 0.2) | 0.83 |
| Insulin concentration (pmol/L) | 104 (68 to 148) | 109 (91 to 159) | −7 (−16 to 2) | 0.14 |
| After midnight‡ | ||||
| Overnight plasma glucose level (mmol/L) | 6.7 (1.0) | 6.8 (2.2) | −0.1 (1.7) | 0.66 |
| SD of overnight plasma glucose level (mmol/L) | 1.2 (0.8 to 1.5) | 1.5 (0.7 to 2.0) | −0.2 (−0.8 to 0.4) | 0.28 |
| Mean amplitude of glucose excursions (mmol/L) | 2.9 (2.3 to 4.1) | 3.9 (1.8 to 5.6) | −0.1 (−2.5 to 0.9) | 0.27 |
| Time plasma glucose spent in target (%)§ | 81 (63 to 99) | 51 (27 to 67) | 32 (6 to 43) | <0.001 |
| Time spent at plasma glucose level (%): | ||||
| ≤3.5 mmol/L | 0 (0 to 0) | 0 (0 to 17) | 0 (−17 to 0) | 0.007 |
| ≤3.90 mmol/L | 0 (0 to 3) | 0 (0 to 27) | 0 (−26 to 0) | 0.04 |
| >8.0 mmol/L | 13 (0 to 34) | 31 (0 to 67) | −8 (−37 to 1) | 0.09 |
| Low blood glucose index | 0.5 (0.1 to 1.1) | 1.2 (0.2 to 4.9) | −0.6 (−4.0 to −0.0) | 0.02 |
| Insulin infusion (U/h) | 0.9 (0.6 to 1.0) | 0.9 (0.6 to 1.0) | 0.1 (−0.1 to 0.2) | 0.46 |
| Insulin concentration (pmol/L) | 81 (48 to 127) | 78 (69 to 124) | 1 (−16 to 13) | 0.20 |
*Closed loop delivery minus insulin pump therapy. Positive value indicates measurement was higher on night of closed loop delivery compared with night of insulin pump therapy.
†From start of closed loop control: 1900 to 0800 in eating in scenario and 2200 to 1200 in eating out scenario.
‡From midnight to 0800 in eating in scenario and from midnight to 1200 in eating out scenario.
§Target range 3.91-8.0 mmol/L.