Energy Balance Following Islet Transplantation

Islet transplantation may be appropriate in up to 10% of adults with Type 1 diabetes who suffer repeated episodes of hypoglycaemia with severely impaired awareness of hypoglycaemia (IAH) (1). Our Scotland-wide islet transplant programme performed its first transplant in February 2011 and 30 islet transplants have followed in 18 recipients. Following islet transplantation we have observed improved glycaemic control in all subjects. When metabolic control is improved with exogenous insulin, weight gain is common (2). In our transplant recipients significant reductions in bodyweight and fat mass with no significant reduction in total caloric intake pre- versus post-transplantation has been observed. We hypothesise that energy expenditure is increased post-transplantation leading to weight loss and diminished fat mass. The mechanisms that may be implicated include increased activity energy expenditure, increased resting energy expenditure (REE) and, or, increased post-prandial thermogenesis (PPT= the energy expended after a meal) secondary to increased portal circulation of insulin being partially or fully restored, and diminished circulating systemic insulin concentrations with a decreased propensity for storing fat. The aim of this study is to understand the mechanism of weight loss and body compositional changes by detailed examination of energy intake and energy expenditure in transplant recipients along with control subjects listed for insulin-pump therapy and glucose tolerant controls. These detailed studies are lacking in islet transplantation and are important as they will reveal how physiology is altered post-transplantation, if peripheral hyperinsulinaemia (insulin-pump subjects and pre-transplant subjects) negatively affects energy expenditure and how quantitative measures such as activity energy expenditure, diet and quality-of-life measures such as fear of hypoglycaemia alter post-transplant. This will lead to the improved management of patients with hypogl