Letters Section Editor: Stephen J. Lurie,
MD, PhD, Senior Editor.
In Reply: In response to Dr Kida, we are unaware
of studies of atubular glomeruli among patients with diabetes and kidney disease
but without albuminuria,1 but this is certainly
an area that should be further investigated.
We disagree with Dr Onuigbo that a random single eye examination underestimated
diabetic retinopathy in our data from the Third National Health and Nutrition
Examination Survey (NHANES III). In the Wisconsin Epidemiologic Study of Diabetic
Retinopathy, only 9% of the 991 subjects had diabetic retinopathy in 1 eye,
while 63% had bilateral disease and the remaining subjects had no retinopathy
(Ronald Klein, MD, MPH, Department of Ophthalmology and Visual Sciences, University
of Wisconsin Medical School, Madison, unpublished data, November 4, 2002).
We believe that a more likely reason for the higher incidence of retinopathy
reported by Gall et al2 and Schwartz et
al3 is referral bias. Gall et al studied
patients attending a diabetes clinic, and the study by Schwartz et al included
patients with type 2 diabetes with proteinuria of greater than 0.5 g/d. Thus,
it is not surprising that disease burden was higher in these referral populations.
The NHANES III data that we used are from a nationally representative survey
and therefore reflect the true burden of disease in the general US population.
All the patients in the study by Nosadini and colleagues4 had
microalbuminuria or macroalbuminuria. The relevance of these findings to our
results is unclear, as we focused on patients with decreased GFR in the absence
of microalbuminuria or macroalbuminuria. Early intervention is beneficial
in patients with diabetes mellitus. Further research is clearly needed to
understand how and why, as reported by Tsalamandris et al, some patients with
diabetes lose renal function in the absence of albuminuria.
Kramer H, Hsu C. Causes of Renal Failure in Patients With Type 2 Diabetes Mellitus. JAMA. 2003;290(14):1855-1856. doi:10.1001/jama.290.14.1855-a