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 hypoglycaemia and IAH.