Standard insulin treatment of type 1 diabetes is sometimes described as “open loop”. This means that insulin doses are decided upon by patients and/or healthcare workers depending on self-monitoring of blood glucose levels. It is not a very satisfactory system – hence the quest for “closed-loop” systems, either pancreas transplantation (segmental or islet cell) or the “artificial pancreas”. The latter is an external or implantable device which infuses insulin in response to continued measurement of tissue glucose levels, the doses being decided by computerised algorithms. Such devices have been intermittently tested for some time, and have been becoming smaller and more sophisticated. This recent Lancet study reports a trial of a “bihormonal” system (i.e. delivering both insulin and glucagon), compared with standard open-loop insulin treatment. The trial was short-term (two 11 week periods) but there was improvement in glycaemic control and reduction in hypoglycaemia in the automated delivery group. This confirms previous studies, and suggests that larger trials (at least 6 months) are now needed.
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