Fear of disease progression and diabetes self-care: Nonlinear associations and moderation by perceived task...

Diabetes is a prevalent chronic condition associated with a substantial health burden. Inadequate self-care is associated with poor glycemic control and increased risk of complications, yet diabetes self-care remains suboptimal. Fear of disease progression (FoP), a broader illness-specific concern, has been underexamined in diabetes and may either motivate or hinder engagement in self-care, suggesting a potential non-linear effect. This study examined whether the relationship between FoP and self-care is moderated by perceived task difficulty and illness perceptions (threat and control).

In a two-wave longitudinal study, 259 participants with diabetes were recruited from an online diabetes patient community in Korea; 187 completed surveys three months apart. Measures included the Fear of Progression Questionnaire, the Brief Illness Perception Questionnaire, and the Summary of Diabetes Self-Care Activities Questionnaire.

Polynomial regression revealed a U-shaped association between FoP and self-care, with lowest self-care at moderate FoP. Task difficulty and threat perception predicted poorer self-care but did not moderate the FoP-self-care link. In contrast, control perception significantly moderated the curvilinear relationship: at low and mean levels of control perception, FoP was linked to declines in self-care, whereas at high control, self-care remained stable across FoP levels.

These findings extend understanding of FoP in diabetes by demonstrating a non-linear relationship with self-care and identifying perceived control as a key moderator. FoP may act as either a motivator or a deterrent depending on its intensity and the individual's control perceptions. Interventions that assess FoP and strengthen perceived control may help sustain self-care in diabetes.