Abstract
Type two diabetes mellitus (T2DM) is in epidemic proportions world wide (1, 2) with obesity being the main driver over the last 30-40 years. Obesity increases the risk of T2DM through an increase in insulin resistance. Establishing the best methods of measuring insulin action have occupied researchers for many years, indicating that no single method can be universally adopted or be suitable for all situations. There are limited data about the effect of bariatric surgery on the measurements of insulin resistance. Recently a new test for the assessment of insulin resistance, the Dynamic Insulin Sensitivity and Secretion Test (DISST), has been developed through the bioengineering department at the University of Canterbury as a suitable substitute for the current but complex “gold standard” reference method, the euglycaemic hyperinsulinaemic clamp (EIC). The DISST method has been validated against the clamp in a range of subjects but not after an intervention which is known to fundamentally change glucose homeostasis and insulin sensitivity. The primary aim of this thesis is to test preliminary performance of DISST relative to the EIC in a morbidly obese cohort before and after bariatric surgery. Secondary aims were assessing the performance of other simple fasting tests against the euglycaemic clamp and also assessing weight, blood pressure and lipid changes in the early post surgery phase.