Good glycemic control has been demonstrated by some to be associated with better cognitive function even in non-T2D individuals. However, strict glycemic control achieved by anti-diabetic medications has been shown to increase risk for morbidity and mortality in some T2D subjects and therefore cannot be homogenously applied. It is therefore relevant and useful as an initial approach to study the association of trajectories in glycemic control over time–reflecting long-term T2D processes rather than glycemic control at a certain period in time, with cognition. Such an approach may form a basis for identification of T2D subjects in which achievement of good glycemic control may be safe and efficacious as a means for dementia prevention. Studies on the relationship of other cardiovascular risk factors and dementia have demonstrated that trends over time–not only mean levels–were associated with increased risk for dementia. Trends in glycemic control among T2D subjects, as reflected in trajectories of repeated HbA1c measurements over years, were associated with mortality. However, to the best of our knowledge, the relationship of such trajectories with cognitive function has not been studied. The present study examined the relationship of empirically developed trajectories of HbA1c levels over time and cognitive function in a cognitively normal cohort of elderly T2D subjects participating in the Israel Diabetes and Cognitive Decline study, a longitudinal investigation of the relationship of long-term T2D characteristics with cognitive decline. The present study demonstrated that among elderly T2D subjects, the trajectories of glycemic control over time were associated with cognitive functioning in the cognitive domains of semantic categorization, executive function and overall cognition. Subjects with a trajectory of decreasing HbA1c levels over the years, were characterized by very high or high HbA1c levels at entry into the DR, and high, though decreasing, HbA1c levels over their T2D course. These subjects had the poorest cognitive performance. Their performance was followed by that of subjects whose HbA1c at entry into the DR was relatively high and increased over time. Subjects with stable HbA1c throughout the years, had the lowest HbA1c levels at all times and performed best in cognitive tests. These analyses were adjusted for sociodemographic, cardiovascular, and T2D-related variables. Trajectories in HbA1c over time were not associated with episodic memory or attention/working memory. Importantly, the trajectories were not defined a-priori and were not based on clinical cutoffs but were rather empirical. Following correction of the analysis for multiple comparisons, the comparison between the most extreme trajectories remained significant in overall cognition, semantic categorization and executive functions. Examining trajectories in HbA1c as predictors of T2D outcomes is advantageous since they describe.