Type 2 diabetes and associated chronic kidney disease (CKD) disproportionately affect blacks. Yet when black and white individuals received comparable diabetes care within the context of a clinical trial, black race was not associated with faster development or progression of CKD. The findings are published in the Clinical Journal of the American Society of Nephrology (CJASN).
The prevalence of type 2 diabetes is higher in non-Hispanic blacks than in non-Hispanic whites, and blacks have an elevated risk of diabetes-related complications. In addition, after development of CKD, blacks with type 2 diabetes are more likely to progress to kidney failure.
It has been unclear whether these burdens may be explained by biological factors that influence propensity to CKD and its severity or by differences in type 2 diabetes care.
To investigate, a team led by Claire Gerber, PhD, MPH, and Tamara Isakova, MD, MMSc, of the Feinberg School of Medicine at Northwestern University, in Chicago, performed a post hoc analysis of a subset of 1937 black and 6372 white middle-aged and older patients with type 2 diabetes who were participating in the Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial. All patients received comparable type 2 diabetes care.
Although people who self-identify as black or African American are underrepresented in pivotal clinical trials for new drug approvals, blacks were adequately represented in the ACCORD trial, comprising 19% of participants. (Blacks constitute 7% of overall clinical trial participants, although they make up 13% of the US population.)
The researchers hypothesized that compared with white participants, black participants with type 2 diabetes who received standardized multifactorial type 2 diabetes care within the context of a randomized controlled trial would have faster kidney function decline and be at greater risk of development and progression of CKD during follow-up. During a median follow-up period of 4 to 5 years, however, black race was not associated with accelerated kidney function decline, and fewer black participants than white participants developed CKD. Specifically, blacks had a 27% lower risk of incident CKD defined by new onset eGFR <60 mL/min/1.73 m2, eGFR decline by >25%, and slope of eGFR decline faster than -1.6 mL/min/1.73 m2.
“In spite of blacks having more risk factors for adverse kidney outcomes in our study, we found that comprehensive type 2 diabetes care within the context of a clinical trial eradicated racial disparities in the development and progression of CKD,” Gerber said.
At the start of the trial, blacks had higher levels of systolic blood pressure and hemoglobin A1c, as well as more frequent macro- and microalbuminuria. During follow-up, however, there were no racial differences in the development of albuminuria.
Isakova noted that the findings are similar to recent results from the Indian Health Service’s first Diabetes Standards of Care implementation effort that delivered comprehensive diabetes care to American Indians and Alaska Natives and eliminated disparities in kidney outcomes in these high-risk populations.
“Taken together, our results and the findings from the Indian Health Service demonstrate that delivery of comparable diabetes care has the potential to achieve equitable health outcomes for all patients with diabetes.”
Nilka Ríos Burrows, MPH, MT, of the Division of Diabetes Translation at the Centers for Disease Control and Prevention, in Atlanta, who was a co-investigator in the American Indians and Alaska Natives study, noted that integrating kidney disease prevention and education into routine diabetes care can help prevent or delay kidney problems.
“The diabetes care team can help patients avoid kidney failure by keeping blood pressure and blood sugar under control, using medicines that lower blood pressure and protect the kidneys, and monitoring kidney function,” she said. “These and other strategies used successfully by the Indian Health Service contributed to reducing kidney failure from diabetes among American Indians and Alaska Natives and can serve as a model to reduce disparities in other populations.”
In an editorial accompanying the CJASN study, Katherine Tuttle, MD, FASN, FACP, of Providence Medical Research Center, in Spokane, WA, called for action. She pointed to numerous areas in which blacks in the United States are disadvantaged across social determinants of health: socioeconomic status, psychosocial factors, healthcare access, neighborhood, and environment. She also pointed to barriers to CKD screening among blacks, including lack of knowledge, mistrust, and financial burden. Key facilitators to screening include CKD education, culturally sensitive communication, and better access by convenient screening.
Gerber C, et al.. Incidence and progression of chronic kidney disease in black and white individuals with type 2 diabetes. Clin J Am Soc Nephrol 2018; 13:884–892.
Bullock A, et al.. Vital signs: Decrease in incidence of diabetes-related end-stage renal disease among American Indians/Alaska Natives—United States, 1996–2013. Morb Mortal Wkly Rep 2017; 66:26–32.