When we think about prediabetes in young people with obesity, we often focus on future physical health risks. But what if it's affecting their minds right now? A small, two-year observational study followed 67 young people with obesity, 42 of whom completed the follow-up. It found that those with prediabetes had lower IQ scores and performed worse on tests of executive function, psychomotor speed, and visuospatial processing at the study's start compared to peers with normal blood sugar.
These cognitive differences between the groups remained stable over the two-year period. The study also found that reduced insulin sensitivity in the body was linked to slower mental processing speed and to changes in how the brain responds to insulin in a specific region involved in thinking. Interestingly, while the group with normal blood sugar showed the expected developmental reduction in brain surface area over time, this pattern was not seen in the youth with prediabetes.
It's crucial to understand what this study does and does not tell us. Because it's an observational study, it can only show an association — it cannot prove that prediabetes causes these cognitive differences. The sample size was small, and we don't know the magnitude of the effects. The findings point to a concerning link that deserves deeper investigation, but they are not yet a reason for alarm or a guide for clinical action.