Impact of Overnight Glucose on Next-Day Functioning in Adults With Type 1 Diabetes: An Exploratory Intensive Longitudinal Study

Abstract

Objective: While there is evidence that functioning, or ability to perform daily life activities, can be adversely influenced by type 1 diabetes, the impact of acute fluctuations in glucose levels on functioning is poorly understood.

Research design and methods: Using dynamic structural equation modeling, we examined whether overnight glucose (coefficient of variation[CV], percent time <70 mg/dL, percent time >250 mg/dL) predicted seven next-day functioning outcomes (mobile cognitive tasks, accelerometry-derived physical activity, self-reported activity participation) in adults with type 1 diabetes. We examined mediation, moderation, and whether short-term relationships were predictive of global patient-reported outcomes.

Results: Overall next-day functioning was significantly predicted from overnight CV (P = 0.017) and percent time >250 mg/dL (P = 0.037). Pairwise tests indicate that higher CV is associated with poorer sustained attention (P = 0.028) and lower engagement in demanding activities (P = 0.028), time <70 mg/dL is associated with poorer sustained attention (P = 0.007), and time >250 mg/dL is associated with more sedentary time (P = 0.024). The impact of CV on sustained attention is partially mediated by sleep fragmentation. Individual differences in the effect of overnight time <70 mg/dL on sustained attention predict global illness intrusiveness (P = 0.016) and diabetes-related quality of life (P = 0.036).

Conclusions: Overnight glucose predicts problems with objective and self-reported next-day functioning and can adversely impact global patient-reported outcomes. These findings across diverse outcomes highlight the wide-ranging effects of glucose fluctuations on functioning in adults with type 1 diabetes.

Graphical abstract

Figure 1

Schematic representation of the estimated DSEMs. A: Model examining lagged within-person relationships between an overnight glucose metric and a next-day functioning measure. B: Model examining a putative within-person mediator of a glucose-functioning relationship. C: Model examining a between-person moderator of the glucose-functioning relationship. D: Model examining a global patient-reported outcome (PRO) predicted by individual differences in the glucose-functioning relationship. The left part in each panel shows the decomposition of the observed variables into within-person (time-varying) and between-person (time-invariant) variance components. The right part in each panel shows the multilevel time series model. B, between person; BG, blood glucose; F, functioning measure; M, putative mediator variable; Mod, moderator variable; s, random regression slope; t, time point; W, within person.