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Rapid Responses to:
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Electronic letters published:
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In Response
Translating "tight control"?
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Michael M Engelgau, MD Centers for Disease Control and Prevention, Linda S. Geiss MS, Dara Murphy MPH, KM Venkat Narayan MD and Frank Vinicor MD
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MXE1{at}CDC.GOV Michael M Engelgau, et al.
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We thank Dr. Finucane for his interest in diabetes translation and his recognition of its importance. He questioned the effectiveness of interventions to improve glycemic control and whether such interventions are ready for translation. We agree with Dr Finucane that no clinical trial has shown that improved glycemic control prevents single endstage microvascular complications such as blindness and kidney disease.1 However, such endstage events are rare and researchers would need to conduct decades of follow-up in order to detect enough cases for meaningful analyses. More often, clinical trials have either examined conditions antecedent to endstage complications (e.g., retinopathy rather than blindness) or combined antecedent and endstage complications into an aggregate measure. For example, results of the Diabetes Control and Complications Trial (DCCT) among persons with type 1 diabetes showed that compared with patients in conventional therapy, those in intensive therapy has 76% less risk of developing new retinopathy and 54% less risk of established retinopathy.2 In the United Kingdom Prospective Diabetes Study (UKPDS) of conventional and intensive glycemic control among persons with newly diagnosed type 2 diabetes 3 researchers developed aggregate outcomes that included several diabetes-related endpoints. “Any diabetes-related end point” included sudden death, death from hyperglycemia or hypoglycaemia, fatal and nonfatal myocardial infraction, angina, heart failure, stroke, renal failure, amputation, vitreous hemorrhage, retinal photocoagulation, blindness in one eye, or cataract extraction. They used this aggregate outcome to compare the results of conventional treatment with results of intensive treatment and found that intensive treatment significantly reduced “any diabetes-related endpoint” (40.9 versus 46.0 events/1000 patient years; p=0.03 The outcome of interventions are dependent on the duration of a patients diabetes, on the duration of the study’s follow-up, and on the quality of care provided outside the clinical trial of glycemic control per se. Observational studies may help sort these issues out. For example, the Wisconsin Epidemiologic Study of Diabetic Retinopathy (WESDR), had a large enough study sample to give us some insight into the risk for end stage disease associated with a given glycemic exposure. 4 For translation, we are interested in multiple endpoints in aggregate, and not necessarily single outcomes, as these aggregate outcomes can greatly affect the quality of life in persons. As such, the evidence for reducing microvascular complications is sound, but we need more direct evidence for the effectiveness to long term endstage complications. Michael M. Engelgau MD Linda S. Geiss MS Dara Murphy MPH KM Venkat Narayan MD Frank Vinicor MD Division of Diabetes Translation National Center for Chronic Disease Prevention and Health Promotion Centers for Disease Control and Prevention Atlanta, GA References 1. Harris R, Donahue K, Rathore SS, Frame P, Woolf SH, Lohr KN. Screening adults for type 2 diabetes: A review of the evidence for the U.S. Preventive Services Task Force. Ann Intern Med 2003;138:215-29. 2. The 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. 3. U.K. Prospective Diabetes Study Group. Intensive blood-glucose control with sulphonnylureas or insulin compared with conventional treatment and risk of complications in patients with type 2 diabetes (UKPDS 33). Lancet1998:352:837-53. 4. Klein R. Hyperglycemia and microvascular and macrovascular disease in diabetes. Diabetes Care 1995;18:258-68. Conflict of Interest:None declared |
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Thomas E. Finucane, MD Johns Hopkins Bayview Medical Center
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tfinucan{at}jhmi.edu Thomas E. Finucane
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In the Annals Supplement “Diabetes Translation and Public Health” (Supplement to June 1, 2004 issue), several of the articles assume or state that careful monitoring and tight control of blood glucose are important in managing type II diabetes mellitus. In the February, 2003, Annals, the United States Preventive Services Task Force presented a table with results from all published randomized controlled trials of “tight control” of type II diabetes(1). If the Metformin arm of the UKPDS, and a multi-intervention STENO2 trial (of 160 patients followed for three years) are excluded, the table can be summarized very briefly. Thousands of patients have been randomized and studied in several trials lasting years. No trial has ever found any benefit from tight control on the endpoints of severe visual impairment, renal failure, amputation, myocardial infarction or all-cause mortality. This mismatch between evidence and recommendation is based on several factors. One is the failure to distinguish clearly between type I and type II diabetes. Murphy and colleagues, for example, note the findings of the DCCT and claim as a “major program implication(s)….that the findings needed to be translated to all persons with diabetes…”.(2) A second is to report the association between higher blood glucose or hemoglobin A1C and worse outcome in patients who were either untreated or were treated without randomization, and then to imply better “control” improves outcome. Engelgau et al report that “the major risk factors….are long term poor glycemic control as measured by both hemoglobin A1C levels and hypertension”. The reference for this remark contains no data that tighter “control” due to a more aggressive treatment strategy will lead to better outcomes.(3) “Diabetes translation” is extremely important. Strong evidence shows that certain interventions can prevent harm from this serious disease. So far, “tight control” is not one of these interventions. Translators should be careful that they have understood the original text correctly and translated it without prejudice. 1. Harris R, Donahue K, Rathore SS, Frame P, Woolf SH, Lohr KN. Screening adults for type 2 diabetes: a review of the evidence for the U.S. Preventive Services Task Force. Ann Intern Med. 2003;138(3):215-29. 2. Murphy D, Chapel T, Clark C. Moving diabetes care from science to practice: the evolution of the National Diabetes Prevention and Control Program. Ann Intern Med. 2004;140(11):978-84. 3. Engelgau MM, Geiss LS, Saaddine JB, et al. The evolving diabetes burden in the United States. Ann Intern Med. 2004;140(11):945-50. Conflict of Interest:None declared |
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