Although ageing is associated with a change in glucose homeostasis with increasing glucose intolerance and hyperglycaemic tendency, hypoglycaemia is not an uncommon complication in older people, hospitalized with acute illness. The development of hypoglycaemia during a hospital admission has been shown to be associated with adverse outcomes. It is likely that the presence of coexisting comorbidities could increase a patient’s vulnerability to both hypoglycaemia and an adverse outcome in the absence of a direct causal link between the two. Therefore, hypoglycaemia can be seen as a biochemical marker of frailty in older people.