Intensive diabetes treatment: a new deal for old people?

Diabetes is predominantly a disorder of the ageing, affecting more than 6% of people over the age of 70 in the United Kingdom (1). Since the most important determinant for the development of the long-term complications of diabetes is duration of hyperglycaemia, elderly people are likely to bear the brunt of the morbidity and mortality associated with diabetes. Until recently, diabetes management in elderly patients was generally aimed at relieving symptoms rather than improving blood glucose control. In part this may have been a consequence of the perception that old age is inevitably a time of decay (2). However, a number of studies have recently described a direct relationship between the achieved standard of glycaemic control and the risk of developing diabetic complications (3)(4)(5). This association is curvilinear, there being no glucose threshold below which individuals are safe from complications. The curvilinear relationship also indicates that any improvement in glycaemic control will produce benefit, especially in individuals who have very high glycosylated haemoglobin [A.sub.1c] ([HbA.sub.1c]) levels. Achieving good glycaemic control may be difficult but is nearly always possible given appropriate patient motivation and adequate input in terms of manpower and resources--one of the major findings from the recently published Diabetes Control and Complications Trial (DCCT) (5).

The DCCT was designed to test the simple hypothesis that the complications of diabetes are related to elevations in plasma glucose levels. The study design was simple. Two groups of patients with insulin-dependent diabetes (IDDM) were followed for an average of 6.5 years; one group was treated conventionally with twice daily insulin therapy and the other group with multiple insulin injections or insulin pumps, monthly clinic visits and frequent (often daily) interaction with a large treatment team including diabetes specialist nurses, dieticians and psychologists as well as physicians. The intensively treated group was clearly distinguished from the standard treatment group in terms of glycaemic control throughout the duration of the study, although average [HbA.sub.1c] levels were consistently above the non-diabetic range. Over the study period there was a 60% reduction in the risk of developing microvascular complications among the intensively treated group. There was also a trend (not statistically significant) for slowing the development of macrovascular disease with intensive therapy. However, these impressive results need to be considered in light of a threefold increased risk of severe hypoglycaemia and an average weight gain of 5 kg during intensive diabetes treatment. Despite more frequent hypoglycaemia, there were no differences between the groups in terms of quality of life or when cognitive function was assessed using formal neuropsychological tests.

Based on the findings from the DCCT, the American and British Diabetes Associations are recommending that intensive diabetes control 'clearly carries significant benefits for patients'. The question is--for which patients? In the DCCT only young (aged less than 40), well motivated patients with IDDM were recruited. Recruitment took place through newspaper advertisements and individuals benefited from 'free' health care. It is unclear whether similar results could (or should) be achieved in an older population or in patients with noninsulin dependent diabetes (NIDDM). The picture may become clearer when the results of the United Kingdom Prospective Diabetes Study are published next year (6). The UKPDS is examining the influence of glycameic control as well as different treatment modialities on the risk of developing complications in older patients with NIDDM and has recruited almost five times as many patients as were in the DCCT.

Of potentially enormous significance is the problem of hypoglycaemia associated with intensive insulin treatment. Although the increased risk of severe hypoglycaemia in the intensively treated group did not adversely influence quality of life scores or neuropsychological assessments, the impact of hypoglycaemia on patients' relatives, friends and workmates was not determined. Furthermore, the risk from the substantial haemodynamic changes associated with hypoglycaemia (including a rise in heart rate, cardiac output and blood pressure) may be difficult to justify in elderly patients with established coronary artery or cerebrovascular disease (7). There is no evidence that intensive diabetic therapy can reverse established macrovascular complications.

The most important message from the DCCT is that improving glycaemic control will produce benefit. Education, motivation and individualized planning are key elements of intensive diabetes care, as opposed to conventional therapy. Unfortunately elderly patients score badly on average in terms of diabetes knowledge (8). At the present time the majority of elderly patients attending hospital are seen by a geriatrician or a diabetologist. There are persuasive arguments for encouraging closer links between both departments (9) with one possible solution being the appointment of geriatricians with a special interest in diabetes. In Bournemouth a joint elderly diabetic clinic has been established with the involvement of a geriatrician, diabetologist and diabetes specialist nurse. General practitioners are encouraged to refer directly to this clinic. The current move towards transferring diabetes care completely from secondary to primary care may have to be re-examined in light of the DCCT results, as studies of long-term care of diabetic patients in general practice have shown significant deficiencies (10)(11). Structured co-operative care between primary and secondary providers, standardized and adequate data collection and audit will be essential pre-requisites for good diabetes management in the future. Good medical practice dictates that resources should be targeted towards interventions which have been shown in clinical trials to produce benefits. The case for improving diabetic control has been made. It remains to be seen whether adequate resources will be made available to improve all aspects of diabetes care both in the hospital and in the community.

DAVID KERR Metabolish Unit, ROBERT HAICH

Department of Elderly Medicine, Royal Bournemouth Hospital, Castle Lane East, Bournemouth

BH7 7DW

References

(1.)Croxson SCM, Burden AC, Bodington M, Botha JL. The prevalence of diabetes in elderly people. Diabetic Med 1991;8:28-31. (2.)Kerr D, Tattersall R. Diabetes and old age. In: Alberti KGGM, Krall LP, eds. The diabetes annual 4. Elsevier Science, B.V., 1988;222-34. (3.)Reichard P, Nilsson B-Y, Rosenqvist U. The effect of long-term intensified insulin treatment on the development of microvascular complications of diabetes mellitus. N Engl J Med 1993;329:304-9. (4.)Wang PH, Lau J, Chalmers TC. Meta-analysis of effects of intensive blood glucose control on late complications of type-1 diabetes. Lancet 1993;341:1306-9. (5.)Diabetes Control and Complications Trial Research Group. The effect of intensive treatment of diabetes on the development and progression of long-term complications in insulin-dependent diabetes mellitus. N Engl J Med 1993;329:977-86. (6.)Multicenter Study. UK Prospective Diabetes Study: II. Reduction in [HbA.sub.1c] with basal insulin supplement, sulfonylurea or biguanide therapy in maturity-onset diabetes. Diabetes 1985;34:793-8. (7.)Kerr D, Stanley JC, Barron M, Thomas R, Leatherdake BA, Pickard J. Symmetry of cerebral blood flow and cognitive responses to hypoglycaemia in humans. Diabetologia 1993;36:73-8. (8.)Knight PV, Cummins AG, Kesson CM. Elderly diabetics--a case for education. J Clin Exp Gerontol 1983;5:285-8. (9.)Sinclair AJ, Barnett AH. Special needs of elderly diabetic patients. Br Med J 1993;306:1142-3. (10.)Hayes TM, Harries J. Randomised trial of routine hospital care versus routine general practice care for type II diabetics. Br Med J 1984;289:728-30. (11.)Wilkes E, Lawton E. The diabetic, the hospital and primary care. J R Coll Gen Practitioners 1980;30:199-206.

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