Abstract Disordered glucose homeostasis and glucose instability are common in older adults. Age is one of the most important risk factors for the development of type 2 diabetes and there is growing evidence that glycemic variability contributes to risk of complications, independent of average glucose or HbA1c. In older adults with diabetes, there is controversy regarding appropriate treatment targets and hypoglycemia is a major concern. Continuous glucose monitoring (CGM) is the recommended approach to the assessment of hypoglycemia and glycemic variability, but this technology has rarely been used in older adults. Very old adults (age 80 years or older) are a particularly vulnerable population but have rarely been included in prior studies. Our overarching objective is to characterize glucose patterns in older adults (>80 years) using state-of-the-art CGM technology. We will characterize “normal” glucose patterns and evaluate the frequency of unrecognized glycemic excursions in adults with and without diabetes (including persons with prediabetes). We will relate glucose patterns including glucose excursions (hypo- and hyperglycemia) to current health status and clinical outcomes during 4 years of follow-up. These results will provide information on the clinical relevance of glucose patterns in an older adult population and generate evidence-based guidance regarding the use and interpretation of CGM in this population.