Modifiable factors important in diabetes-related kidney decline
medwireNews: Findings from the ARIC cohort show that diabetes increases the rate of long-term kidney function decline, but a proportion of this is accounted for by modifiable risk factors.
“Given the well-established evidence that glycemic control prevents or slows microvascular damage, our findings reinforce the need for early diagnosis of diabetes and glycemic control following diagnosis,” write the researchers in Diabetes Care.
During 26 years of follow-up, the estimated glomerular filtration rate (eGFR) among 13,698 ARIC participants without diabetes (88% of the cohort) declined at an average annual rate of 1.6 mL/min per 1.73 m2. It declined 0.6 mL/min per 1.73 m2 faster in 634 (4%) participants who had undiagnosed diabetes at baseline and 1.3 mL/min per 1.73 m2 faster in 1185 (8%) with diagnosed diabetes at baseline.
These differences were significant and remained so, albeit slightly reduced, after accounting for diabetes and kidney disease risk factors.
However, Morgan Grams (Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA) and co-researchers noted large variations in the rate of kidney function decline between individual participants, particularly among those with diabetes, in whom the average annual decline ranged from 2.0 to 4.1 mL/min per 1.73 m2.
After adjusting for diabetes and kidney disease risk factors and antidiabetic medication use, variables that significantly accounted for faster individual declines in kidney function were Black race, the high-risk APOL1 gene variant, hypertension, current smoking, insulin use, and baseline glycated hemoglobin (HbA1c) of 9% or higher.
“Although the APOL1 high-risk genotype is a known risk factor for eGFR decline, African Americans with low-risk APOL1 status continued to be at higher risk than whites even after adjustment for traditional risk factors, diabetes medication use, and HbA1c,” notes the research team.
“This suggests there could be differences over time by risk factors, diabetes severity, access to health care, quality of health care, or health care utilization not accounted for in our analysis.”
Of note, the eGFR decline in patients with undiagnosed diabetes at baseline occurred only after the first 3 years of follow-up, and “followed a period of relatively little average eGFR decline, which may reflect early hyperfiltration,” say Grams and team.
Indeed, the decline during the first 3 years was actually less than that among people without diabetes, leading the researchers to warn that eGFR may not be an appropriate surrogate marker of kidney function in patients with recently diagnosed diabetes.
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