Clinical and Metabolic Predictors of Cognitive Impairment in Type 1 Diabetes: The Role of Peripheral Neuropathy and Hypoglycaemia Unawareness. Findings From a HAD‐1 Study

Aims This study evaluated the impact of selected clinical factors on cognitive impairment (CI), particularly diabetic peripheral neuropathy (DPN) and impaired awareness of hypoglycaemia (IAH) in individuals with long‐standing type 1 diabetes (T1D). Materials and Methods In this cross‐sectional Hypoglycaemia Awareness Study in Diabetes Type 1 (HAD‐1), 252 adults with T1D were enrolled. Cognitive function was assessed using the Montreal Cognitive Assessment (MoCA), with CI defined as a MoCA score < 26. IAH was identified using validated questionnaires (Clarke scale, Gold scale and Hypoglycaemia Awareness Questionnaire). Results The median MoCA score was 26 (23–28). CI was present in 122 subjects (48%), DPN in 85 subjects (34%) and IAH in 98 patients (39%). In univariate linear regression analysis, lower MoCA scores were associated with higher HbA1c ( β = −0.30 and p = 0.017), older age ( β = −0.03 and p = 0.014), a greater number of lifetime severe hypoglycaemia (SH) episodes ( β = −0.17 and p = 0.001), DPN ( β = −1.09 and p = 0.01) and higher skin autofluorescence ( β = −0.72 and p = 0.03). In the multivariable regression analysis, IAH ( β = −1.41 and p < 0.001), male sex ( β = −0.89 and p = 0.022), higher HbA1c ( β = −0.47 and p < 0.001) and higher vibration perception threshold ( β = −0.049 and p = 0.004) were independent predictors of lower cognitive performance. Higher insulin dose ( β = +2.92 and p = 0.012) was independently associated with better cognitive performance. In the interaction model, IAH ( β = −1.54 and p = 0.003) and DPN ( β = −1.18, p = 0.040) were independently associated with approximately 1.2–1.5‐point lower MoCA scores. Conclusions In individuals with T1D, DPN and IAH, a history of SH, poorer metabolic control, older age and male sex are associated with CI. People with T1D should be screened for CI, especially if they have DPN or IAH.