on et al, 2005) compared with those with no depression.
The US National Health and Nutrition Examination Survey found that diabetes patients with depression were 2.5 times more likely to die from all-cause mortality and 2.43 times more likely to die from coronary heart disease than the general population (Egede et al, 2005). Finally, a longitudinal study of Mexican Americans with type 2 diabetes aged 65 years and over were found to be almost five times more likely to die if depressed at a seven-year follow-up and were significantly more likely to develop an earlier onset of diabetes complications than those without depression (Black et al, 2003).
Having depression and diabetes has significant costs to individuals and society but the mechanisms that start to explain why this is the case are complex and thought to involve interactions between biological, psychological and social processes.
Simple psychological explanations suggest people with depression and diabetes are less likely to look after themselves and perform adequate self-management, evidence of which is seen in the literature.
Social explanations might also add to this, for example if people are depressed they may be more likely to be socially isolated, without social support and perhaps at a disadvantage in maintaining good personal relationships. This can have far-reaching consequences, limiting their capacity for work and study, and increasing their chances of experiencing poverty.
Biological explanations suggest depression influences cardiovascular health and macrovascular complications through activation of the hypothalamic pituitary adrenal axis or through immune system dysfunction (McCaffery et al, 2006). In depression, the hypothalamic pituitary axis is overstimulated and the associated sympathetic response may increase cardiovascular risk in several ways. For example, more counter-regulatory stress hormones that raise blood-glucose levels are released leading to insulin resistance (Brotman et al, 2007); there is also increased platelet activity and atherosclerosis (Musselman et al, 1996), and altered autonomic tone leading to decreased heart rate variability (Carney et al, 1995).
Genetic and environmental interactions may also play a role - obesity, insulin resistance and hypertension tend to be grouped together (Stunkard et al, 2003). Common effects of depression are listed in Box 1.
Depression screening, management and support
Depression in people with diabetes was recognised by the NHS as a priority; depression screening was included in the UK diabetes review but has recently been removed from the Quality and Outcomes Framework assessment. NICE (2009) guidelines suggest GPs and practice nurses play an active role in assessment. Recommendations for treating mild depression include:
- Watchful waiting by the primary care health team;
- Guided self-help;
- Computerised cognitive behavioural therapy;
- Brief psychological interventions and exercise.
For moderate to severe depression, more complex psychological interventions and pharmacotherapy are recommended.
Many nurses will be familiar with the two-item screen for depression, which asks patients if they have low mood or have lost interest in everyday activities. If the patient answers “yes” to either question, the degree of depressive symptoms is then assessed with a validated questionnaire such as the Patient Health Questionnaire (Kroenke et al, 2001) or the Hospital Anxiety and Depression Scale (Zigmond and Snaith, 1983). A positive score on either does not mean the patient has depression but does indicate they should be assessed by an experienced clinician.
Some patients with diabetes may not realise they have depression; instead they may report having difficulty managing their diabetes, perhaps linked to increased symptoms, and are at the point of giving up on their self-management. Others may report anxiety or eating problems, which may be related to depression, such as emotional eating, binging or purging.
Now routine screening in primary care settings is no longer part of the QOF assessment, so