Introduction and background: In type 1 diabetic patients good glycaemic control is associated with complication reduction. Nevertheless a minority of patients, also treated with insulin pumps and continuous glucose monitoring (SAP therapy) achieve a satisfactory metabolic control. Several researchers are developing automatic systems, called artificial pancreas (AP) or Closed Loop Control (CLC). This system are composed by an insulin pump, a continuous glucose monitoring device and a control algorithm which modifies insulin infusion from data derived by continuous glucose monitoring. Several AP models exist, composed by different insulin pumps, different continuous glucose monitoring system and by different control algorithms that determine the precision of glucose control.
Method: we evaluated our AP model efficacy and safety at patients home compared to SAP therapy. In our AP model, the Algorithm is installed in a smartphone (DiAS, Diabetes Assistant) that communicate with pump and CGM thought blue tooth connection. We developed 5 studies that tested the system in free life condition, first during evening and night, than for 24 hours and for longer period (6 months). We finally evaluated this system in pediatric population.
Results: In a randomized cross over study of 2 month AP use during evening and night vs SAP therapy, system usage improved time in target (70-180 mg/dl) from 58.1% to 66.7% ( P < 0.0001), reduce mean glucose concentration (162 mg/dl vs 167 mg/dl, P=0.0053) and time spent in hypoglycemia (<70 mg/dl) from 3.0% to 1.7% (P < 0.0001) and lead to reduction in HbA1c values. Extension of this study for a month using AP 24 hours/day demonstrated an improvement of time in target vs SAP (64.7 ± 7.6% vs. 59.7 ± 9.6%, P = 0.01), reduction of time below the target (1.9 ± 1.1% vs. 3.2 ± 1.8%, P = 0.001).
A third trial evaluated a different algorithm for 2 weeks during overnight e for 2 weeks for 24 hours, comparing these period with 2 weeks of SAP therapy. In overnight period AP improved glucose metric vs SAP: time spent in hypoglycaemia dropped from 3.0% to 1.1% (P < 0.001), time in target increased from 61% to 75% (P < 0.001) , time spent above 180 mg/dl dropped from 37% to 24% (P < 0.001), the mean glucose concentration dropped from 163 to 150 mg/dL (P = 0.002). Similarly, metrics of glucose control in the 24-hour AP usage vs SAP demonstrated reduction of the time below target from 4.1% to 1.7% (P < 0.001), increase of time in target from 65% to 73% (P < 0.001), decrease of time above target from 32% to 25% (P = 0.001). Comparing the overnight and 24 hours CLC, a reduction in time spent in hypoglycaemia was observed when AP was used for 24 hours. A subgroup of patients extended AP use for other 5 months, confirming AP efficacy (time in target:77% vs. 66%, P<0.001, time in hypoglycaemia: 4.1% vs 1.3%, P < 0.001, time above target 31% vs 22%, P = 0.01). Finally we tested the system in paediatric population, enrolling in a summer camp 30 subject 5-9 years old. During the night AP reduced time in hypoglycaemia (P < 0.002), with no difference in time in target. During 24 hours we observed reduction of the time in hypoglycaemia, from 6.7% to 2.0% (P < 0.001), but an increase of mean glucose (147 mg/dL vs. 169 mg/dL, P < 0.001) and a decrease of time spent in target (63.1% vs. 56.8%, P = 0.022)
Conclusions: These results demonstrated our model safety and efficacy. Some improvements are necessary to ameliorate glycaemiec control on pediatric population and during day time
