The effect of type 2 diabetes mellitus on health-related quality of life (HRQOL).

Improving the quality of life of all South Africans has become a major concern to health care practitioners, organisations and politicians. However, the paucity of local information on health-related quality of life (HRQOL) does not allow us to address this public health challenge. In order to rectify this deficiency and complement international research, we undertook a study with 281 Type 2 Black diabetic patients and 437 controls, with no self-reported chronic conditions, to ascertain HRQOL. We used the SF-20 to measure functioning, general health, well-being and bodily pain (HRQOL). It was hypothesised that diabetes mellitus significantly affects functioning, general health and well-being. Multiple analyses of covariance controlled for age, schooling, marital status, employment status and commodity ownership (a socio-economic measure). Patients were significantly more likely to report poorer role functioning, poorer general health and more pain than controls, providing partial support for the hypothesis. Reliability (internal consistency) coefficients on the four multi-item SF-20 sub-scales ranged between 0.79 (well-being), 0.81 (general health), 0.83 (physical functioning) and 0.94 (role functioning) for patients: for controls these coefficients ranged between 0.70 (well-being), 0.78 (general health), 0.80 (physical functioning) and 0.90 (role functioning). Inter-correlations among the sub-scales were significant for patients and controls (p = 0.01). It was concluded that the SF-20 is a reliable instrument for measuring HRQOL in both patient and control samples, and diabetes mellitus has more impact on general health and level of pain than on well-being.