The present study investigated the perceptual, attentional and memory processes underlying face recognition deficits observed in older adults with impaired glucoregulation. Participants were categorised as good glucoregulators or poor glucoregulators on the basis of an oral glucose tolerance test (OGTT). Using event-related potential (ERP) methodology, 23 participants (18 females, range = 62 to 88 years old, mean age = 73.87 years old, SD = 8.41) performed a 2-stimulus oddball task. Participants were asked to rate and memorise 10 ‘target’ faces, which were then presented amongst 120 unfamiliar foils. Behavioural results indicated that good glucoregulators were significantly more accurate at recognising target faces. ERP markers of early visual perception (the P1 and N170 components) and memory formation (the P3 component) were unaffected by glucoregulatory efficiency. The P2 component, an index of attentional processing, was larger and delayed in the poor glucoregulators. To the best of our knowledge, the present study is the first to suggest that face recognition deficits in poor glucoregulators may be due to impairments in attentional processing.