Potentially Dangerous treatment
The authors recommend—and reinforce this recommendation with a question in the CME test—an optimal value for glycated haemoglobin (HbA1c) of below 7%, in order to counteract the development and progression of diabetic retinopathy.
In support of this they cite the DCCT study (1), but this study was conducted in patients with type 1 diabetes. Whether the results translate to patients with type 2 diabetes is not only questionable but has been disproved by the results of the large studies of type 2 diabetes. The UKPDS 33 (2) is incorrectly cited: lowering HbA1c from 7.9% to 7.0% does not reduce the need for laser coagulation of the retina by one third but by a rather more modest amount—namely, from 11 per 1000 patient years to 7 per 1000 patient years. Doctors and patients will have to reach a joint decision about whether the price of achieving this objective is not rather too high when considering the additional rate of severe hypoglycemias (which require help from third parties) of 7% for glibenclamide and 11% for insulin per 10 years.
HbA1c was lowered to less than 7% in only in 3 larger studies (3, 4, 5). The retinopathy rate did not fall in any of these three studies. Why the authors recommend a potentially dangerous treatment (hypoglycemias, excess mortality as in ACCORD) remains a mystery.
Dr. med. Günther Egidi
Huchtinger Heerstr. 41
28259 Bremen, Germany
Conflict of interest statement
The author declares that no conflict of interest exists according to the Guidelines of the International Committee of Medical Journal Editors.