It is a happy coincidence in the history of medicine that the means available to treat Type I diabetes (the type that usually starts in childhood and requires lifetime treatment with insulin) became available just as its incidence was rising sharply. Such diabetes was rare in the nineteenth century but was rapidly fatal. Pediatricians at the beginning of the twentieth century had few patients with diabetes, and this was not because they failed to recognize it when they saw it. Since the middle of the twentieth century, however, Type I diabetes has become much more common, suggesting an environment cause – yet to be fully elucidated.
Although insulin keeps many alive who would once have died, Type I diabetics continue to suffer long-term ill-effects and complications, among them eye, kidney and peripheral vascular disease. It is though that the better the control of blood sugar levels, the later and less serious the complications.
One of the problems that bedevils treatment is that blood sugar can be lowered too far, and low blood sugar itself leads to complications and sometimes to fatality. The fear of hypoglycaemic attacks is a constant one for diabetics. The aim of treatment is to keep blood sugar at normal levels without inducing such attacks.
A paper in a recent edition of the New England Journal of Medicine describes treatment with a kind of pump that continually alters the rate of insulin according to the level of the patient’s blood sugar. The investigators, in Britain and Germany, treated 58 patients with Type I diabetes with this pump for 12 weeks to see whether it improved control of blood sugar levels compared with normal treatment.
They found that it did. The percentage of the time when the blood sugar of the treated patients was within the proper range increased, 11 percent for adults and 24.7 percent for children and adolescents, without either an increase in the number of hypoglycaemic attacks or an increase in the total amount of insulin infused. Both undesirable peaks and troughs were avoided when the new pump was used.
Patients acted as their own controls; their blood sugar levels were compared when they did and did not use the new pump. This was valid because the results could not have been affected by a placebo effect.
The study, importantly, was carried out in naturalistic rather than laboratory conditions. The patients continued their lives as normal; they went about their daily lives and ate what they normally ate (irrespective of whether or not it corresponded to what was advised for them). This is important, because many trials take place in such artificial or controlled conditions that it is impossible to know whether the results are transferrable to real-life circumstances. A treatment may be very effective in a trial, but fail to work in practice because patients do not take it properly. This trial avoids that pitfall.
It is too soon, however, to conclude that it represents a giant step forward in the treatment of Type I diabetes. It seems to stand to reason that if the complications of such diabetes are caused by poor control of the level of blood sugar, and if the new pump assists in producing better control of that level, then it ought to help in reducing the level of those complications. However, this type of reasoning is always hazardous in medicine: the proof of the pudding is always in the eating. It is all too easy to treat biochemistry rather than patients. The better control of blood sugar levels is not an end in itself. It is worthwhile only if it actually leads to clinical benefit, and that has yet to be shown, and this will take a long time.
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