Abstract The prevalence of both cognitive dysfunction and diabetes is increasing. Research shows that diabetes increases the risk for cognitive impairment and the rate of cognitive decline doubles after diabetes is diagnosed. In turn, cognitive dysfunction can make diabetes self-management more difficult. Diabetes self- management, essential to good glycemic control, requires both the assimilation of knowledge regarding a complex disease and self-management activities such as glucose self-monitoring and medication management. The objective of this R21 application is to pilot test the Memory, Attention, and Problem-Solving Skills for Persons with Diabetes (MAPSS-DM) intervention, a comprehensive cognitive rehabilitation intervention, which will include examining patterns of glycemic variability using continuous glucose monitors (CGMS). The central hypothesis of this proposal is that persons who received the MAPSS-DM intervention will have improved memory and executive function, greater use of compensatory strategies, and improved self- management. We will also explore the role of glucose variability in those changes. The specific aims of this proposal are as follows: Aim 1. To test the efficacy of the MAPSS-DM intervention for improving cognitive function, A1C, and diabetes self-management. Sixty-six participants with cognitive concerns and diabetes will be randomly assigned to either the full MAPSS-DM intervention or an active control. This pilot study will provide estimates of effect size on the following outcomes: A1C, diabetes self-management, and cognitive function. Aim 2. To explore changes in glycemic variability and their association with changes in cognitive function and diabetes self-management. Participants will use continuous glucose monitors pre-, during, and post- intervention to identify changes in glycemic variability related to the intervention. This project is innovative because it will be the first study to test lifestyle-based online cognitive rehabilitation as an intervention in T2DM. Providing cognitive rehabilitation that incorporates a widely available and increasingly acceptable technology (CGMS) is an innovative way to measure the impact of the intervention. This study will fill an important gap by addressing cognitive function in the management of diabetes. The results will contribute to the development of the knowledge necessary to enact strategies to support cognitive function and diabetes self-management which is significant because diabetes is related to accelerated cognitive aging, cognitive deficits are related to poorer self-management, and improvements in cognitive performance as a result of cognitive rehabilitation can translate into improved performance in everyday life and potentially diabetes self-management. Furthermore, the proposed study will offer new mechanistic insights into cognitive function through use of CGMS.