Longitudinal Associations Between Illness Perceptions and Glycemic Control in Type 2 Diabetes

Cross-sectional research demonstrates associations between illness perceptions and glycemic control in people with type 2 diabetes (T2D). Prospective studies are limited and show mixed findings. This study aimed to investigate (1) whether baseline illness perceptions predicted glycemic control (HbA1c levels) at 6-12-month follow-up and (2) possible differences in baseline illness perceptions between individuals who completed at least one HbA1c blood test during the 12-month follow-up and those who did not.

A total of 115 individuals with T2D were recruited from an outpatient clinic. Demographic and clinical information and illness perceptions were assessed at baseline. HbA1c was assessed at baseline and 12 months later from clinical records. Hierarchical multiple linear regression examined associations between baseline illness perceptions and HbA1c levels at 6-12-month follow-up, controlling for age, sex, education, types of diabetes medication, and baseline HbA1c.

Univariate analysis showed perceived weight management effectiveness at baseline was associated with lower HbA1c at follow-up (rho = -.25, p = .04, n = 67). Adjusted multiple regression showed that HbA1c at baseline was the only significant predictor of HbA1c at 6-12-month follow-up (β = 0.51, p < .001). There were no significant differences in baseline illness perceptions between individuals who completed HbA1c blood tests during follow-up (n = 78) and those who did not (n = 34), p > .05.

Illness perceptions at baseline did not predict longitudinal HbA1c in adjusted analyses, nor completion of HbA1c tests. Results may be due to temporal variability in HbA1c and barriers to accessing blood tests.