Letter by Watada et al Regarding Article, “Two-Year Clinical Outcomes With Drug-Eluting Stents for Diabetic Patients With De Novo Coronary Lesion”
To the Editor:
We read with interest the article by Dr Ortolani and coworkers1 on the results of their study of 2-year clinical outcome of drug-eluting stents for diabetic patients. They concluded that the use of drug-eluting stents was associated with a modest reduction in the 2-year risk of target vessel revascularization compared with the use of bare-metal stents. In their study, a significant reduction in risk of major adverse cardiac events by drug-eluting stent implantation was identified in non-insulin-dependent diabetic patients but not in insulin-dependent diabetic patients. However, after a careful reading of their article, we noticed that the term “insulin-dependent diabetes” was used by the authors in a manner inconsistent with the established guidelines.2,3
“Insulin-dependent diabetes mellitus” is a term used to describe diabetes mellitus that requires insulin therapy to avoid ketoacidosis.4 This term does not encompass patients who use insulin therapy solely for the control of blood glucose level. In most cases, the pathogenesis of insulin-dependent diabetes mellitus is autoimmune in nature. According to the guideline of the American Diabetes Association, this form of diabetes mellitus is classified as type 1 diabetes.2 Although the incidence of insulin-dependent diabetes mellitus differs around the world, it is estimated that only about 5% to 10% of North American diabetic individuals have insulin-dependent diabetes mellitus.5 In comparison, 27% of the patients described in the study of Ortolani et al1 were labeled as insulin dependent. Even though the authors did not provide their definition of insulin-dependent diabetes, we assume the reported higher rate was probably an overestimation due to the use of the term “insulin-dependent diabetes” as synonymous with insulin-requiring (or insulin-using) diabetes rather than strictly those patients requiring insulin therapy to avoid ketoacidosis.
Is this clinically important or pure semantics? Because diabetes mellitus is an established risk for the development of restenosis after stent implantation, it is important to search for the type of diabetes that is closely linked to the restenosis event. Multiple risk factors for the progression of atherosclerosis are often identified in diabetic patients (eg, insulin resistance, hyperglycemia, abdominal obesity, and hyperinsulinemia). Obviously, clear differences exist between non-insulin-dependent and insulin-dependent diabetes mellitus. For example, whereas most non-insulin-dependent diabetic individuals in Western countries are obese and insulin resistant, insulin-dependent diabetic individuals are not necessarily obese or insulin resistant. For a better understanding of the pathophysiological link between diabetes mellitus and cardiovascular disease, we should be diligent in using definitions consistent with the guideline.
Ortolani P, Balducelli M, Marzaroli P, Piovaccari G, Menozzi A, Guiducci V, Sangiorgio P, Tarantino F, Geraci G, Castriota F, Tondi S, Saia F, Cooke RM, Guastaroba P, Grilli R, Marzocchi A, Maresta A. Two-year clinical outcomes with drug-eluting stents for diabetic patients with de novo coronary lesions: results from a real-world multicenter registry. Circulation. 2008; 117: 923–930.
Report of the Expert Committee on the Diagnosis and Classification of Diabetes Mellitus. Diabetes Care. 1997; 20: 1183–1197.
World Health Organization Consultation Group. Definition, Diagnosis, and Classification of Diabetes Mellitus and its Complications, 2nd ed. Part 1: Diagnosis and classification of diabetes mellitus. Geneva, Switzerland: World Health Organization; 1999: 1–59.
World Health Organization Study Group. Diabetes mellitus. Technical Report Series 727. Geneva, Switzerland: World Health Organization; 1985.
Diagnosis and classification of diabetes mellitus. Diabetes Care. 2008; 31 (Suppl 1): S55–S60.