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The notion that there may be environmental β cell toxins is supported by the existence of chemicals that cause an insulin‐dependent type of diabetes in animals. Examples are alloxan and streptozocin, both of which damage the β cell at several sites, including membrane disruption, enzyme interaction (e.g. with glucokinase) and DNA fragmentation. The rat poison vacor causes type 1 diabetes in humans, possibly because it has a similar action to streptozocin.

Figure 6.7 Potential mechanisms of viral aetiology of autoimmune and non‐autoimmune type 1 diabetes. IL = Interleukin; IFN = Interferon; TNF = Tumour Necrosis Factor.

Adapted from Craig ME et al Pediatr Diabetes 2013;14:149–58.

Figure 6.8 Proposed mechanisms of β cell death. β cells die through a process known as apoptosis, characterised by condensation and fragmentation of nuclear chromatin, loss of cytoplasm and expression of surface receptors that signal macrophages to ingest the apoptotic cell. Apoptosis is effected by activation of the caspase pathway.