C URRENT O PINION Bringing closed-loop home: recent advances in closed-loop insulin delivery Hood Thabit and Roman Hovorka Purpose of review To highlight the recent advances in closed-loop research, the development and progress towards utilizing closed loop outside of the clinical research setting and at patients’ homes. Recent findings In spite of the modern insulin therapy in type 1 diabetes, hypoglycaemia is still a major limiting factor. This often leads to suboptimal glycaemic control and risk of diabetes complications. Closed loop has been shown to improve glycaemic control whilst avoiding hypoglycaemia. Incremental progress has been made in this field, from the use of automated systems and bihormonal closed-loop systems in clinical research facility settings under close supervision to the use of ambulatory closed-loop prototype at patients’ homes in free-living conditions. Different population of patients with type 1 diabetes and control algorithm approaches have been studied, assessing the efficacy and safety. Transitional and home studies present different challenges at achieving better glycaemic outcome with closed loop. Improved glucose sensor reliability may accelerate the clinical use and faster insulin analogues increase the clinical utility. Summary Results and experience with closed-loop insulin delivery have been encouraging, leading the way for future improvements and development in the field, to make closed loop suitable for use in clinical practice. Keywords algorithm, ambulatory, automated, closed-loop, home studies INTRODUCTION The ultimate goal of diabetes therapy is to maintain normoglycaemia and avoid diabetes-related compli- cations. Glycaemic control with insulin therapy in type 1 diabetes is influenced by insulin-dependent factors such as insulin kinetics, dosage and timing of insulin delivery [1,2], as well as physiological fac- tors, such as effects of circadian rhythm and illness on insulin sensitivity [3–6]. Unfortunately, one of the known risks of tightening glycaemic control with insulin is hypoglycaemia [7]. The complexities of managing insulin therapy in daily life can, there- fore, be overwhelming for some patients with type 1 diabetes, resulting in suboptimal control. Utiliz- ation of real-time continuous glucose monitoring (CGM) and modern continuous subcutaneous insu- lin infusion (CSII) therapy has been reported to improve the overall glycaemic control [8,9,10 & ]. However, studies have shown that the benefits of these devices are limited to certain age groups and those who are motivated [11 – 13]. Closed-loop insu- lin delivery, also known as the artificial pancreas, may potentially be beneficial in improving the glycaemic control in type 1 diabetes, until a bio- logical cure can be found. Closed-loop systems deliver insulin in a contin- ued glucose-responsive manner by coupling subcu- taneous CGM and subcutaneous insulin pump delivery [14]. This novel approach differs from the conventional pump therapy by the use of a control algorithm, which autonomously directs insulin delivery based on real-time sensor glucose levels. Significant advances have been made in this field over the last 2 years. Closed-loop systems have pro- gressed from manual input, in which researchers Wellcome Trust-MRC Institute of Metabolic Science, University of Cambridge, Cambridge, UK Correspondence to Roman Hovorka, PhD, University of Cambridge Metabolic Research Laboratories, NIHR Cambridge Biomedical Research Centre, Wellcome Trust-MRC Institute of Metabolic Science, Box 289, Addenbrooke’s Hospital, Hills Road, Cambridge, CB2 0QQ, UK. Tel: +44 1223 762 862; fax: +44 1223 330 598; e-mail: rh347@ cam.ac.uk Curr Opin Endocrinol Diabetes Obes 2014, 21:95–101 DOI:10.1097/MED.0000000000000048 1752-296X ß 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins www.co-endocrinology.com REVIEW