2008 Clinical Practice Guidelines - Canadian Diabetes Association

2008 CLINICAL PRACTICE GUIDELINES
S126
Chronic Kidney Disease in Diabetes
Canadian Diabetes Association Clinical Practice Guidelines Expert Committee
The initial version of this chapter was written by Philip McFarlane MD FRCPC and
Bruce Culleton MD FRCPC
KEY MESSAGES
• Identification of chronic kidney disease (CKD) in diabetes
requires screening for proteinuria, as well as an
assessment of renal function.
• All individuals with CKD should be considered at high
risk for cardiovascular events, and should be treated to
reduce these risks.
• The progression of renal damage in diabetes can be
slowed through intensive glycemic control and optimization
of blood pressure. Progression of diabetic nephropathy
can be slowed through the use of medications that
disrupt the renin-angiotensin-aldosterone system.
INTRODUCTION
Chronic kidney disease (CKD) is one of the most common and
potentially devastating complications of diabetes. Fifty percent
of people with diabetes have CKD, and CKD associated with
diabetes is the leading cause of kidney failure in Canada (1-4).
CKD in diabetes can be due to classic diabetic nephropathy or
other forms of kidney damage. Classic diabetic nephropathy
progresses from subclinical disease to the earliest clinically
detectable stage characterized by persistent proteinuria
(2,5,6) (Figure 1).The degree of proteinuria is characterized
as either microalbuminuria (urinary albumin 30 to 300 mg/day)
or overt nephropathy (urinary albumin >300 mg/day) (Table
1). Typically it takes many years to progress through these
stages (2,7,8), and significant renal dysfunction is not usually
seen until late in the course (9). Because type 2 diabetes can be
unrecognized for a long time prior to diagnosis, it is possible
for renal disease, including advanced nephropathy, to be present
at the time of diagnosis of type 2 diabetes (10,11).
Although diabetic nephropathy is common, as many as
50% of people with diabetes and significant renal dysfunction
have normal urinary albumin levels with renal disease
that is not related to classic diabetic nephropathy (12). For
example, hypertensive nephrosclerosis and renovascular disease
are common causes of CKD in people with diabetes.
Table 2 lists indicators that favour the presence of renovascular
disease.The risk of end-stage renal disease in diabetes
does not appear to vary significantly whether the kidney disease
is related to diabetic nephropathy or alternative renal
diagnoses (13). Thus, identification of CKD in diabetes
requires screening for proteinuria, as well as an assessment
of renal function.
Regardless of the cause, the stage of kidney disease can be
classified based on the level of renal function (Table 3). In the
case of diabetes, the kidney damage associated with stage 1 or 2
CKD manifests as persistent albuminuria (see Screening, p. S127).
It is also important to recognize that people with CKD
are among those at highest risk for cardiovascular (CV) morbidity
and mortality, and that interventions to lower CV risk
remain the most important priority in this population
(14,15).
Figure 1. Stage of diabetic nephropathy by level of urinary albumin by various
test methods
Urine test
Urine dipstick
0
Normal
24-hour 30 mg/day
ACR (male) 2.0 mg/mmol
ACR (female) 2.8 mg/mmol
ACR = albumin to creatinine ratio
Stage of nephropathy
Microalbuminuria Overt nephropathy (macroalbuminuria)
Negative
300 mg/day
20.0 mg/mmol
28.0 mg/mmol
Positive
Urinary Albumin Level
1000 mg/day
66.7 mg/mmol
93.3 mg/mmol