There is little doubt that kidney transplantation is the most desirable treatment for patients requiring renal replacement therapy. It is also clear that the deceased donor pool is a limited and finite resource. Living kidney donation has the potential to impact overall numbers of patients receiving those organs and as well as opening a space on the deceased donor list. Another truism is that the clinical outcomes of living donor recipients are better than those receiving deceased donor kidneys, as a whole. The major tenet of living donation since its beginning has been the safety of the donor, both in the short and long terms. In the short term, efforts are directed to limit risks of anesthesia, operative techniques, and the postoperative recovery. Long-term considerations are concentrated on remaining renal function and maintenance of the same. Because of the successes of living donor kidney transplantation, programs have chosen to push the envelope increasing access to living donors. As living donor programs have matured, acceptance of nonrelated donors and even altruistic donors have become common. Living donor age has increased over time, and some programs have allowed individuals with mild, controlled hypertension to donate. In this issue, Hebert et al1 have studied the past use of living kidney donors with compromised glucose control.
This article considers the impact of isolated impaired fasting glucose (IFG) in living donors without other identified comorbidities. They utilize data from 3 large living donor kidney centers and publicly available data from The Renal Lung Living Donor Evaluation study. These 3 centers contacted donors for follow-up data on the development of diabetes, hypertension, kidney disease, cardiovascular disease, cancer, or other health conditions. The study period spans from 1963 to 2007, and as a result of the changing guidelines for diabetes and IFG over this time period, allows for examination of long-term outcomes of patients selected for living donation which, by older criteria, were selected to donate with imperfect glucose control. They postulated that IFG would not subject these donors to a higher risk of future renal dysfunction, compared to those with normoglycemia. They conclude that living kidney donors with IFG “do well in the short- and intermediate-term and the risk of ESKD in those with fasting glucose >126 mg/dL at the time of donation is comparable to people with two kidneys.” They further state that they would propose that “potential kidney donors with impaired fasting glucose be considered for donation after they receive formal counseling” regarding their risks and need for compliance to guidelines for their future glucose management.
This study suffers from many weaknesses of its design. It is predicated on a registry/survey database which relies on collection of remotely obtained data points. However, considering the length of the follow-up period of included patients it is remarkably complete with only 7% of 8922 donors excluded for a lack of glucose testing in follow-up. Several of the pieces of data are collected only at a single point in time. Years from donation to study closure is relatively short in the big picture, varying from a mean of 11.5–14.3 y. The graphic representation of the cumulative incidence of individual outcomes show diverging curves, with mortality, hypertension, diabetes, proteinuria, and lower GFR’s increasing over time when normal fasting sugars are compared to those with IFGs. Ideally, it would be desirable to have longer follow-up time periods in that diabetic renal disease may take longer to develop. This is clearly a selected population of healthy individuals chosen to donate. The comparator group of age-adjusted US population diabetes data provided by the CDC are probably a different population, in that the study population is clearly a selected group of healthy individuals chosen to donate who are provided with routine follow-up health care postdonation.
While not the definitive trial that we seek, this adds important information to our repertoire. This is clearly the largest study addressing this question, considering the available number of patients to follow over time and that the study population includes individuals over nearly 50 y of living donation. Transplant teams make difficult decisions every day regarding the suitability of the patients they care for. None are more difficult than the safety of a potential donor who derives very little benefit from the procedure itself. This study provides even more information that allows the clinician to provide counseling to the potential donor as to the long-term risks of donating a kidney. It is probably even more important for an older donor, who is dedicated to donation, to further understand the risks as they have a more finite window for longevity. These data provide another tool that can guide our clinical decision making in this difficult environment. As importantly, the more information that we can provide our patients do help to empower them to make rational decisions. Routine utilization of donors with mild impaired glucose metabolism needs careful consideration and we should not simply sugar coat it.
Knowledge is power. Information is liberating. Education is the premise of progress, in every society, in every family.
Secretary General of the UN (1997–2006)
1. Hebert SA, Murad DN, Nguyen DT, et al. Outcomes of kidney donors with impaired fasting glucose. Transplantation. 2022;106:138–146.