Tracking mental health and cognitive changes following the Australian social media minimum age legislation: a 4-wave longitudinal study protocol.

Diabetes mellitus is a chronic metabolic condition characterized by impaired insulin production or utilization, leading to persistent dysregulation of blood glucose levels []. Beyond its well-established vascular and metabolic complications, diabetes substantially increases the risk of cognitive impairment, with prevalence estimates reaching up to 58% of affected individuals [, ]. Cognitive deficits in diabetes span multiple domains, including memory, attention, executive function, language, and visuospatial abilities, [] and carries significant clinical consequences. These deficits interfere with social functioning, [] undermine diabetes self-management behaviors [], and ultimately elevate the risk of complications and reduce quality of life. The mechanisms linking diabetes to cognitive decline are multifactorial, involving insulin resistance, chronic inflammation, oxidative stress, and vascular injury []. Among these, glycemic control has emerged as a particularly critical determinant of cognitive health []. Uncontrolled glucose and hyperinsulinemia disrupt neuronal metabolism, intensify oxidative stress and inflammation, and impair synaptic and mitochondrial function.[] Over time, these processes compromise neuronal integrity, leading to structural brain damage and cognitive deterioration []. Traditionally, glycated hemoglobin (HbA1c) has served as the primary biomarker of long-term glycemic control. However, HbA1c provides only an average estimate over 3 months and fails to capture short-term fluctuations or daily variability, which may exert independent and potentially stronger effects on cognitive outcomes. Continuous glucose monitoring (CGM) addresses these limitations by providing real-time, high-resolution glucose profiles and enabling the assessment of dynamic metrics such as time in range (TIR; percentage of time within a target glucose range), mean amplitude of glucose excursion (MAGE; magnitude of major glucose swings), and coefficient of variation (CV; relative glucose variability). CGM is increasingly regarded as the gold standard for characterizing glycemic patterns in both clinical care and research [, ] and offers a unique opportunity to elucidate the complex relationship between glucose dynamics and cognitive outcomes in diabetes. Although this field remains nascent, emerging evidence suggests that glucose variability—captured by metrics such as CV and postprandial glucose excursions—may contribute to cognitive decline independently of average glucose levels.[, ].