The Relation of Ambulatory Blood Pressure and Pulse Rate to Retinopathy in Type 1 Diabetes Mellitus: The Renin–Angiotensin System Study
Received 12 October 2005; accepted 5 June 2006. published online 21 September 2006.
Purpose
To examine the association of ambulatory blood pressure (ABP) and ambulatory pulse rate (APR) with diabetic retinopathy (DR) in persons with type 1 diabetes in the Renin–Angiotensin System Study (RASS), a multicenter primary diabetic nephropathy (DN) prevention trial.
Design
Cross-sectional study.
Participants
One hundred ninety-four normotensive RASS participants in 3 centers who are 16 years of age or older with type 1 diabetes mellitus (DM) of 2 to 20 years’ duration.
Methods
Ambulatory blood pressure and APR were monitored using standardized protocols. Patients were defined as nondippers if the night-to-day ratios for both systolic and diastolic blood pressures were >0.9. Diabetic retinopathy was determined by masked grading of 30° color stereoscopic fundus photographs of 7 standard fields using the Early Treatment Diabetic Retinopathy Study severity scale.
Main Outcome Measure
Severity of DR.
Results
No DR was present in 32%, mild nonproliferative DR (NPDR) was present in 55%, and moderate to severe NPDR or proliferative DR was present in 13% of the cohort. Neither 24-hour systolic ABP or diastolic ABP, daytime systolic or diastolic ABP, nor nighttime diastolic ABP were related to severity of DR. Statistically significant associations were found between nighttime systolic ABP and mean ABP and DR. Among those with no DR, 19% were nondippers; for those with mild NPDR, 28% were nondippers; and for those with severe NPDR or proliferative DR, 36% were nondippers (P = 0.08). The ratio of nighttime to daytime APR, but not the 24-hour APR or daytime or nighttime APR, was related positively to the severity of DR. In multivariable analyses, only the nighttime systolic ABP was related to severity of DR (P<0.05).
Conclusions
These data suggest that ABP, especially during the night, may provide a better measure than clinical BP regarding the relationship of BP to the severity of retinopathy in normotensive persons with type 1 DM without clinical DN.
1Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin.
2Department of Pediatrics, University of Minnesota, Minneapolis, Minnesota.
3Department of Medicine, Leadership Sinai Center for Diabetes, Mount Sinai Hospital, University of Toronto, Toronto, Canada.
4Department of Medicine, McGill University, Montreal, Canada.
5Department of Epidemiology and Biostatistics, McGill University, Montreal, Canada.
6Department of Medicine, Saint Michaels Hospital, University of Toronto, Toronto, Canada.
7Department of Pediatrics, McGill University, Montreal, Canada.
Correspondence to Ronald Klein, MD, MPH, Department of Ophthalmology and Visual Sciences, University of Wisconsin–Madison, 610 North Walnut Street, 460 WARF, Madison, WI 53705-2397.
Manuscript no. 2005-978.
Supported by the National Institute of Diabetes and Digestive and Kidney Disease, Bethesda, Maryland (grant no.: DK51975); Merck & Co., Whitehouse Station, NJ; Merck Frosst, Montreal, Canada; and Canadian Institutes of Health Research, Ottawa, Canada (grant no.: DCT 14281). The University of Minnesota General Clinical Research Center is supported by the National Institutes of Health, Bethesda, Maryland (grant no.: M01 RR 00400). Additional support was provided by the National Eye Institute, Bethesda, Maryland (grant no.: EY12198), and Research to Prevent Blindness, Inc., New York, New York (Senior Scientific Investigator Award [RK]).
The authors do not have any conflicts of interest related to the article.
ABSTRACT