Exploring the role of glucagon in glucose homeostasis

The aim of this thesis was to gain further insight into the role of glucagon in glucose homeostasis in healthy volunteers and type 2 diabetes mellitus (T2DM) patients, and to explore the novel antisense glucagon receptor antagonist. Chapter 2 showed that the effect of meal replacers containing protein hydrolysate on plasma glucose lowering is limited in T2DM patients due to a collective increase of both insulin and glucagon levels. In chapter 3 and 4 a glucagon challenge test in healthy volunteers and T2DM was studied and showed a good reproducibility and no confounding changes in autonomic nervous system tone. T2DM patients respond profoundly different to a glucagon challenge test compared to healthy volunteers and the response to a glucagon challenge test in T2DM subjects is influenced by the type of therapy. Chapter 5 provided the first proof of pharmacology of a novel antisense glucagon receptor antagonist in humans, ISIS 325568, as reflected by a reduction in glucagon-induced glucose excursion by using a well-characterized glucagon challenge test. In chapter 6 we designed a semi-mechanistic model which simultaneously describes glucagon, plasma glucose, insulin and glucagon receptor internalization using data from glucagon challenges in healthy volunteers.