Initially discovered as an impurity in
insulin preparations, our understanding of the hyperglycaemic
hormone glucagon has evolved markedly over subsequent decades. With description of the precursor
proglucagon, we now appreciate that
glucagon was just the first
proglucagon-derived
peptide (PGDP) to be characterised. Other bioactive members of the PGDP family include
glucagon-like peptides -1 and -2 (GLP-1 and GLP-2),
oxyntomodulin (OXM),
glicentin and
glicentin-related pancreatic peptide (GRPP), with these being produced via tissue-specific processing of
proglucagon by the
prohormone convertase (PC)
enzymes, PC1/3 and PC2. PGDP
peptides exert unique physiological effects that influence metabolism and energy regulation, which has witnessed several of them exploited in the form of long-acting, enzymatically resistant analogues for treatment of various pathologies. As such, intramuscular
glucagon is well established in rescue of hypoglycaemia, while GLP-2 analogues are indicated in the management of
short bowel syndrome. Furthermore, since approval of the first
GLP-1 mimetic for the management of
Type 2 diabetes mellitus (T2DM) in 2005,
GLP-1 therapeutics have become a mainstay of T2DM management due to multifaceted and sustainable improvements in glycaemia, appetite control and
weight loss. More recently, longer-acting PGDP
therapeutics have been developed, while newfound benefits on cardioprotection, bone health, renal and liver function and cognition have been uncovered. In the present article, we discuss the physiology of PGDP
peptides and their therapeutic applications, with a focus on successful design of analogues including dual and triple
PGDP receptor agonists currently in clinical development.