Investigating the association between diabetes mellitus, depression and psychological distress

1057 December 2015, Vol. 105, No. 12 Diabetes mellitus (DM) and depression are highly preva lent conditions, and each contributes significantly to morbidity and mortality worldwide. The number of people with DM globally is projected to rise from 171 million in 2000 to 366 million in 2030,[1] and develop­ ing countries are likely to carry an increased share of this burden. While data are limited for South Africa (SA), there is evidence that this burden is already considerable, with the prevalence of type 2 DM estimated at 28.2% in a recent community­based study in Bellville South, Cape Town.[2] The estimated prevalence of major depressive episodes (MDE) in SA is also high, based on the findings of the South African Stress and Health (SASH) study.[3] The prevalence of MDE in SA was found to be 9.7% and 4.9% for lifetime and a 12­month period, respectively.[3] Poor health behaviours associated with depression, such as smoking, physical inactivity and high caloric intake, may increase the risk of type 2 DM.[4] Depression is also associated with physiological abnormalities, including activation of the hypothalamic­pituitary­ adrenal axis, sympathoadrenal system and proinflammatory cytokines, which can induce insulin resistance and contribute to diabetes risk.[4] Furthermore, the sense of threat of debilitating complications and the lifestyle changes associated with management of diabetes may increase the risk of depression.[4] A meta­analysis of 39 studies reported that 11% of patients with DM met the criteria for comorbid major depressive disorder.[5] Another meta­analysis that examined the relation between depression and diabetes onset found that the risk of developing type 2 DM was 37% greater in depressed adults than in adults without depression.[6] SA has a quadruple burden of disease: a combination of poverty­ related infectious diseases, violence­related injuries, perinatal and maternal disease, and an increase in lifestyle­related non­commu­ nicable diseases (NCDs).[7] The potential link between depression, psychological distress and DM may therefore be particularly relevant and warrants further investigation. SA teachers, in common with teachers everywhere, have high job stressors related to time pressures, the educational system, prof­ essional distress and learner misbehaviour.[8] Job stress and lack of job satisfaction are associated with many stress­related illnesses, including hypertension, heart disease, stomach ulcers, asthma, mental distress and alcohol misuse.[8] We investigated the association between DM, depression and psycho logical distress in a pilot cohort of SA teachers. Specific objectives of this study were to: (i) describe the demographic and clinical profile of the cohort; (ii) determine the prevalence of DM, depression, and psychological distress; and (iii) determine whether DM is associated with depression and psychological distress.