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Study Summary This cross-sectional study analyzed data from 531 Mexican American adults with diabetes who were enrolled in the Family Blood Pressure Program. Through the use of stereoscopic fundus photography, subjects were classified into 1 of 4 categories of increasing diabetic retinopathy. Subjects also underwent echocardiography to assess cardiac structure and function. Associations between the echocardiographic results and retinopathy status were assessed with statistical models to adjust for differences in age, sex, body mass index (BMI), blood pressure, hypertension status, microalbuminuria status, previous cardiovascular disease, glycated hemoglobin (HbA1c), cholesterol, and smoking status.
Subjects averaged about 61 years of age, and nearly two thirds were women. There were 126 (23.7%) individuals without diabetic retinopathy, 231 (43.5%) with early nonproliferative diabetic retinopathy, 107 (20.2%) with moderate-to-severe nonproliferative diabetic retinopathy, and 67 (12.6%) with proliferative diabetic retinopathy. More severe retinopathy was associated with systolic blood pressure, previous cardiovascular disease, hypertension, longer duration of diabetes, higher HbA1c, and greater albuminuria. Left atrial dimension and left ventricular mass increased as the category of retinopathy severity increased, associations that persisted after controlling for age, sex, BMI, systolic and diastolic blood pressure, hypertension status, microalbuminuria status, previous cardiovascular disease, HbA1c, cholesterol, and smoking status. Left ventricular ejection fraction and midwall shortening decreased with increasing severity of retinopathy after adjustment for the above confounders.ViewpointOne important limitation of the current study is that glycemic control was very poor (HbA1c levels, 9.5%-11.4%) across all levels of retinopathy. Whether the study's findings generalize to patients with better glycemic control is unknown. Nevertheless, we often think of complications of diabetes as being either microvascular or macrovascular in nature. This thinking is due in part to studies, such as the United Kingdom Prospective Diabetes Study, that demonstrated microvascular but not macrovascular benefits from tight glycemic control.[1] The current study is an important reminder that such thinking is an oversimplification. This reminder is especially important as we digest the findings of the ACCORD (Action to Control Cardiovascular Risk in Diabetes) trial, ADVANCE (Action in Diabetes and Vascular disease: PreterAx and DiamicroN-MR Controlled Evaluation) trial, and VADT (Veterans Affairs Diabetes Trial) that failed to find a cardiovascular benefit to intensive glycemic control.[2-4] Those results should not be taken to mean that tight glycemic control will not provide long-term cardiovascular benefits. It may be that microvascular complications of diabetes manifest earlier than macrovascular complications, meaning that much longer trials would be necessary to realize a macrovascular benefit. Because previous studies have linked retinopathy to an increased risk for cardiovascular disease[5] and heart failure,[6] it is possible that the benefits of treatments that reduce the risk for microvascular disease will ultimately reduce macrovascular disease as well, even if the macrovascular benefit takes many years to realize. In any case, patients typically feel better when their glycemic control and blood pressure control are good, and that is of the utmost importance.Abstract [ CLOSE WINDOW ]References1. UK Prospective Diabetes Study Group. Intensive blood-glucose control with sulphonylureas or insulin compared with conventional treatment and risk of complications in patients with type 2 diabetes (UKPDS 33). UK Prospective Diabetes Study (UKPDS) Group. Lancet. 1998;352:837-853. Abstract 2. Action to Control Cardiovascular Risk in Diabetes Study Group; Gerstein HC, Miller ME, Byington RP, et al. Effects of intensive glucose lowering in type 2 diabetes. N Engl J Med. 2008;358:2545-2559. Epub 2008 Jun 6. 3. ADVANCE Collaborative Group; Patel A, MacMahon S, Chalmers J, et al. Intensive blood glucose control and vascular outcomes in patients with type 2 diabetes. N Engl J Med. 2008;358:2560-2572. Epub 2008 Jun 6. 4. Duckworth W, Abraira C, Moritz T, et al; VADT Investigators. Glucose control and vascular complications in veterans with type 2 diabetes. N Engl J Med. 2009;360:129-139. Epub 2008 Dec 17. 5. Cheung N, Wang JJ, Klein R, Coupler DJ, Sharrett AR, Wong TY. Diabetic retinopathy and the risk of coronary heart disease: the Atherosclerosis Risk in Communities Study. Diabetes Care. 2007;30:1742-1746. Epub 2007 Mar 26. 6. Wong TY, Rosamond W, Chang PP, et al. Retinopathy and risk of congestive heart failure. JAMA. 2005;293:63-69. Abstract |
