Psychological aspects of the Diabetes Control and Complications Trial

I would like to comment upon some of the issues raised by the Diabetes Control and Complications Trial! from a psychological point of view, and to discuss their broad clinical implications. First, and most importantly, the Trial demonstrated that good metabolic control can delay the onset and slow progression of diabetes-related complications. To do this, a complicated regimen was required. This raises the question of how much inconvenience patients are prepared to put up with for the sake of long-term future benefits. In the intensively-treated group, tight control was achieved by selfmonitoring blood glucose at least four times per day, three or more daily injections of insulin via syringe or pump, adjustment of insulin dosage where necessary, attention to the timing, content and frequency of meals together with changes in activity and exercise patterns. You might think that all of this, together with monthly clinic visits and regular telephone contacts would be regarded as unacceptably intrusive by many patients. However, only 1% of patients failed to complete the study; an astonishingly low drop-out figure. Further, patients completed a 46-item questionnaire that was specifically designed to measure the burden of the disease and the treatment regimen. It was found that the quality of life of patients receiving intensive therapy was no worse than that of patients receiving conventional treatment. Intensive therapy significantly increased the risk of severe hypoglycaemia. Patients in the intensively treated group experienced severe hypoglycaemia three times more frequently than conventionally managed patients. Half of all hypoglycaemic episodes occurred during sleep and about one third of daytime hypoglycaemic episodes occurred without warning. It is known from other studiesthat repeated severe hypoglycaemia can lead to slight but measurable impairments in some aspects of memory and cognitive functioning. However, as part of the Trial, patients completed tests of neuropsychological functioning: no patients experienced neuropsychological impairments. What are the lessons for everyday clinical practice? First, a note of caution. The patients who took part in the Trial are probably not typical of patients with Type 1 diabetes. They were self-selected, younger and highly motivated. They received close monitoring by highly skilled research teams. It will be difficult to achieve the same levels of attention and the same levels of glucose control in typical, unselected populations of patients. It is unrealistic to expect otherwise. The researchers themselves pointed out that the frequency of severe hypoglycaemia might be higher when tight control is sought in everyday clinic conditions. This will be a particular risk in certain groups such as youngsters, for whom the risk of brain damage makes repeated severe hypoglycaemia potentially dangerous. Furthermore, although quality of life was no different between the treatment groups, the links between such things as quality of life, treatment adherence, mood disturbances (such as depression) and metabolic control are far from clears, Again, we must be cautious about generalising the findings from the Trial too enthusiastically. So, although our understanding of the relationship between blood glucose and complications. has been advanced, there is still a long way to go. In particular, knowing how best to help patients achieve and maintain control remains a major challenge for health services.