Midlife Type II diabetes mellitus (T2DM) is an important yet often unrecognized risk factor for the later development of dementia. We conducted a systematic review to assess the efficacy of non-pharmacological interventions (namely diet, exercise and cognitive training) for T2DM on cognition. A search strategy was constructed and applied to four databases: EMBASE, Medline, CINAHL and Web of Science. Peer-reviewed journal articles in English were considered assessing the effect of exercise, dietary or cognitive training/stimulation-based interventions (or any combination of these) in patients with T2DM on cognition. Results were dual-screened and extracted by two independent reviewers. Of 4820 results, 3782 remained after de-duplication. Forty full-texts were screened and two studies were included in the final review. The first assessed the impact of a 10-year intensive lifestyle intervention on T2DM-related complications (Look-AHEAD study) and the second was a post hoc analysis of T2DM patients from a trial of a physical activity intervention in older non-demented adult with functional limitations (LIFE study). Whilst the Look-AHEAD study found no impact on diagnosis of mild cognitive impairment or dementia, the LIFE study demonstrated beneficial effects on global cognitive function and delayed memory specifically in older adults with T2DM. There is insufficient evidence to fully assess the effect of non-pharmacological interventions on cognition in T2DM. Well-constructed trials must be designed to specifically assess the effect of non-pharmacological and multi-domain interventions for cognition in patients with T2DM in midlife. All trials examining interventions in T2DM should consider cognition as at least a secondary outcome.
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