The associations of anxiety, depression and personal illness representations with glycaemic control and health-related quality of life in patients with type 2 diabetes mellitus

OBJECTIVE: This study examined the interrelationships of anxiety, depression and personal illness representations with glycaemic control and health-related quality of life in adults with Type 2 diabetes. METHODS: One hundred eighty-four consecutive patients with Type 2 diabetes mellitus completed the Illness Perception Questionnaire (IPQ), the Well-Being Scale (WBQ) and the Short Form 36 Health Survey Questionnaire (SF-36). Demographic characteristics, details of diabetes status (duration of diabetes, treatments and complications) and glycosylated haemoglobin (HbA1c) were recorded. RESULTS: Depression was correlated with greater perceived symptom load (r = .48, P < .01), worse anticipated consequences (r = -.41, P < .01) and perceived lack of control of diabetes (r = .28, P < .01). After controlling for demographic and illness characteristics, personal illness representations relating to symptom load and anticipated consequences were independently associated with the SF-36 physical functioning score, contributing an additional 15% to the variance. WBQ depression and anxiety scores, along with IPQ control and consequences, were independently associated with SF-36 mental function score, contributing a further 51% to the variance after controlling for demographic and illness details. Neither IPQ nor WBQ scales were associated with HbA1c after controlling for demographic and medical illness details. CONCLUSION: Anxiety, depression and negative beliefs about illness influence physical and mental functioning, but not metabolic control in patients with diabetes.