Hyperinsulinaemia, the pancreatic response to insulin resistance, is linked with obesity and type 2 diabetes. Obesity is a known risk factor for certain types of cancer, including gastrointestinal, breast, endometrium and pancreas, but the ‘umbrella’ of obesity covers multiple factors which may increase cancer risk. These include diet, physical activity, type 2 diabetes, obesity hormones such as leptin and adiponectin, insulin resistance and hyperinsulinaemia. Analysing the individual contribution of these factors is complex but there is evidence to suggest that hyperinsulinaemia is associated with increased risk of some cancers.
This evidence ranges from animal and epidemiological studies to observational clinical data and indicates that the effect of insulin on cancer risk is via growth proliferation (mitogenicity) rather than carcinogenesis. The development of insulin analogues with different degrees of mitogenicity provides insights into the interaction of insulin with the insulin and IGF‐1 receptors and the understanding of these interactions has offered an explanation for the differential effect of hyperinsulinaemia on cell proliferation compared with glucose metabolism.
Metformin, as an insulin sensitiser, appears to reduce cancer risk, as do the accepted strategies for reducing risk associated with obesity: diet (particularly low fat) and physical exercise. Copyright © 2020 John Wiley & Sons.