Insulin: new roles for an ancient hormone

Area of Science:

• Endocrinology
• Metabolic Research
• Cardiovascular Science

Background:

• Classical insulin action focuses on glucose metabolism and homeostasis.
• Insulin resistance and deficiency disrupt glucose control via hyperinsulinaemia and glucose toxicity.
• Emerging research reveals novel insulin functions beyond glucose regulation.

Purpose of the Study:

• To review and synthesize recent findings on the expanded roles of insulin.
• To explore the implications of insulin resistance and hyperinsulinaemia in various physiological processes.
• To highlight the connection between these expanded insulin actions and cardiovascular disease.

Main Methods:

• Review of in vitro and in vivo studies on insulin's physiological and molecular actions.
• Analysis of data linking insulin resistance to dyslipidaemia, pro-thrombotic states, and oxidative stress.
• Examination of insulin's effects on renal function, membrane potential, thermogenesis, and central nervous system activity.

Main Results:

• Insulin inhibits lipolysis and platelet aggregation; resistance promotes pro-thrombotic states.
• Hyperinsulinaemia may be pro-oxidant; insulin resistance linked to defective thermogenesis.
• Insulin influences sodium/uric acid excretion, blood pressure, and cardiovascular parameters (QT interval, vasodilation).
• Central insulin effects mimic a stress response.

Conclusions:

• Insulin's functions extend beyond glucose metabolism to cardiovascular, renal, and central nervous system regulation.
• Insulin resistance and chronic hyperinsulinaemia have widespread detrimental effects, contributing to cardiovascular risks.
• Further research is needed to fully understand these complex roles and their clinical implications.