Effect of basal insulin and omega 3 fatty acids on cognitive impairment in dysglycaemia: An exploratory analysis of the ORIGIN trial

Abstract

Aim: The outcomes reduction with an initial glargine intervention (ORIGIN) trial reported that, allocation to insulin glargine-mediated normoglycaemia versus standard care, and to omega 3 fatty acids versus placebo had a neutral effect on cognitive test scores when analysed as continuous variables. Analyses of these scores as standardized categorical variables using a previously validated strategy may yield different results. Materials and Methods: The ORIGIN trial recruited participants with dysglycaemia and additional cardiovascular risk factors from 573 sites in 40 countries. They completed a mini mental state examination and a subset completed the digit symbol substitution test at baseline and up to three subsequent visits. The effect of the interventions on country-standardized substantive cognitive impairment, defined as the first occurrence of a baseline-adjusted follow-up mini mental state examination or digit symbol substitution test score ≥1.5 standard deviations below the baseline mean score in each participant's country was assessed using Cox proportional hazards models. Results: During a median follow-up of 6.2 years, 2627 of 11 682 people (22.5%) developed country-standardized substantive cognitive impairment. The hazard of this outcome was reduced by 9% (hazard ratio 0.91, 95% confidence interval 0.85, 0.99; p =.023) in participants assigned to insulin glargine (21.6%) versus standard care (23.3%). Conversely, the hazard of this outcome was not affected by assignment to omega 3 fatty acid versus placebo (hazard ratio 0.93, 95% confidence interval 0.86, 1.01; p =.074). Conclusions: In this post hoc exploratory analysis, insulin glargine-mediated normoglycaemia but not omega 3 fatty acids reduced the hazard of substantive cognitive impairment in people with dysglycaemia and additional cardiovascular risk factors.