Insulin Sensitivity After Living Donor Nephrectomy

Abstract

The kidney is essential for glucose and insulin metabolism. Living kidney donors (LKDs) experience a reduction in glomerular filtration rate of 25 to 30 mL/min after donor nephrectomy. Little is known about the effect of glomerular filtration rate decline on insulin sensitivity in LKDs. We conducted a prospective pilot study on 9 LKDs (N=9) who underwent dynamic metabolic testing (mixed meal tolerance test) to measure proxies of insulin sensitivity (homeostatic model assessment of insulin resistance, the area under curve [AUC] for insulin/glucose ratio, and Matsuda insulin sensitivity index) before and 3 months after donor nephrectomy. The primary outcome was the change in insulin sensitivity indices (delta [post-nephrectomy - pre-nephrectomy]). Four of the donors had a body mass index (BMI) between 32.0 and 36.7 predonation. Post-donor nephrectomy, compared with prenephrectomy values, median insulin AUC increased from 60.7 to 101.7 hr*mU/mL (delta median 33.3, P=.04) without significant change in median glucose AUC levels from 228.9 to 209.3 hr*mg/dL (delta median 3.2, P=.77). There was an increase in the median homeostatic model assessment of insulin resistance from 2 to 2.9 (delta median 0.8, P=.03) and the AUC insulin/glucose ratio from 30.9 to 62.1 pmol/mmol (delta median 17.5, P=.001), whereas the median Matsuda insulin sensitivity index decreased from 5.9 to 2.9 (delta median -2, P=.05). The changes were more pronounced in obese (BMI >32) donors. LKDs appear to have a trend toward a decline in insulin sensitivity post-donor nephrectomy in the short term, especially in obese donors (BMI >32). Further investigation with a larger sample size and longer follow-up is needed.