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HbA1c, BP may affect diabetic kidney disease progression
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Among adults with type 1 diabetes, those with higher HbA1c and blood pressure levels may be more likely to develop diabetic kidney disease, according to findings published in the Journal of Diabetes and its Complications.
“The definition of [diabetic kidney disease] has expanded to include the presence of albuminuria at any level of kidney function or renal function decline in the absence of detectable albuminuria,” Janet B. McGill, MD, Endocrine Today Editorial Board Member and professor of medicine and director of the fellowship in endocrinology, diabetes and metabolism at Washington University School of Medicine in St. Louis, and colleagues wrote. “Despite recommendations for improvements in glucose control, blood pressure and greater use of renin-angiotensin system (RAS) blockers over the past decades, persons with [type 1 diabetes] continue to develop albuminuria and loss of kidney function.”
McGill and colleagues assessed kidney function for at least 5 years in 3,940 participants in the T1D Exchange Clinic Network and Registry (mean age, 41 years; 55% women; median diabetes duration, 19 years). Participants had an estimated glomerular filtration rate of at least 60 mL/min/1.73 m2 at recruitment (2010-2012). The researchers used clinical medical records to ascertain follow-up data, including use of continuous glucose monitoring, HbA1c levels, BP and the presence of albuminuria, which was confirmed when albumin-to-creatinine ratios rose to at least 30 µg/mg in back-to-back readings. The researchers also monitored eGFR and noted an “adverse renal outcome” when measures fellow below 60 mL/min/1.73 m2.
The researchers found that the average ages of participants who either had an eGFR below 60 mL/min/1.73 m2 (53 years) or had such a rate in addition to albuminuria (55 years) were higher than for those who retained normal kidney function (P = .01). Of the 268 participants who developed albuminuria, 68% were younger than 19 years when diagnosed with type 1 diabetes compared with 32% who were diagnosed after age 19 years (P < .001). A greater percentage of those who had either an eGFR of less than 60 mL/min/1.73 m2 (54% vs. 46%) or albuminuria and depleted eGFR (51% vs. 49%) after follow-up were younger than 19 years when diagnosed with type 1 diabetes compared with those diagnosed at older ages (P < .001 for both).
The average HbA1c levels for those with albuminuria (8.1%), eGFR below 60 mL/min/1.73 m2 (7.9%) or both (8.2%) were higher than for those who did not reach such renal thresholds (7.6%; P < .001 for all), according to the researchers. Average systolic BP was 125 mm Hg for those with albuminuria, 123 mm Hg for those with an eGFR of less than 60 mL/min/1.73 m2 and 129 mm Hg for those with both albuminuria and an eGFR below 60 mL/min/1.73 m2 vs. 122 mm Hg for those with normal kidney function (P < .001). In addition, the researchers noted that participants with either an eGFR below 60 mL/min/1.73 m2 or such a rate in addition to albuminuria had reduced diastolic BP (70 mm Hg) vs. those with normal kidney function (73 mm Hg; P < .001).
“The modestly higher HbA1c among those with incident [diabetic kidney disease] compared to those without is a reminder that glucose control across the life span continues to be an important factor in the development of diabetes complications and that poor metabolic control early in the disease may have long-term consequences,” the researchers wrote.
According to the researchers, fewer than half of the participants with some form of impaired kidney function used CGM (47%), including only 38% of those with both albuminuria and an eGFR below 60 mL/min/1.73 m2, whereas 56% of those without kidney dysfunction reported CGM use (P = .04). The researchers also noted that 50% of those with some form of impaired kidney function had a bachelor’s degree or more compared with 63% of those with normal kidney function (P = .03).
“The high rate of reduced eGFR without albuminuria attests to the need to monitor both albuminuria and serum creatinine with calculation of eGFR to diagnose this important diabetes complication,” the researchers wrote. “Our findings also indicate that both age and duration of diabetes are important risk factors and suggest that surveillance for [diabetic kidney disease] should continue across the age spectrum in adults.” – by Phil Neuffer
Disclosure: This study was funded by the Leona M. and Harry B. Helmsley Charitable Trust
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