Early Postural Instability with History of COVID-19 Influence Related to Diabetes: An Exploratory Cross-Sectional Study

Background/Objective: In late adulthood, the increasing prevalence of diabetes overlaps with the highest prevalence of postural instability. A cross-sectional study was designed to explore the combined influence of age, gender, history of COVID-19 quadriceps strength, and Body Mass Index (B.M.I.) on the postural stability of adults with/without diabetes, under a variety of sensory conditions. Methods: A total of 263 adults aged 21 to 82 years old accepted to participate, 99 with and 164 without diabetes. They had no history of vestibular/otology/neurology/autoimmune/orthopedic disease or proliferative retinopathy/severe renal dysfunction/traumatic injury. After clinical and vestibular evaluations, postural sway was recorded on hard/soft surface, eyes open/closed, and without/with 30° neck extension. Bivariate analysis and repeated measures multivariate analysis of covariance were performed with 0.05 significance. Results: In the two groups, two thirds of the participants had excess weight and almost half had history of COVID-19. Overall conditions, gender and diabetes were the main factors contributing to sway area (multiple R = 0.28–0.31, p ≤ 0.001) and to sway length (multiple R = 0.34–0.47, p ≤ 0.00001). Compared to adults without diabetes, in those with diabetes, the age was not related to sway measurements; with contribution to sway from history of COVID-19 and quadriceps strength, and decreased contribution of the study variables to both the anterior–posterior position of the center of pressure and ankle movement (velocity as a function of the anterior–posterior position of the center of pressure) (p > 0.05). Conclusions: Diabetes may interfere with the influence of individual cofactors contributing to postural sway, including decreased influence of age and reduced ankle movement. A history of mild–moderate COVID-19 may have influence on postural control in varied sensory conditions.