The following is a summary of “Renal Cortical Glucose Uptake Is Decreased in Insulin Resistance and Correlates Inversely With Serum Free-fatty Acids,” published in the April 2024 issue of Endocrinology by Rebelos, et al.
Research on human renal metabolism is limited, but advancements in functional imaging have enabled the noninvasive characterization of renal metabolism. Recent studies have utilized fluorodeoxyglucose F18 (18F FDG) positron emission tomography to analyze renal glucose uptake (GU) rates, revealing the renal cortex as an insulin-sensitive tissue. For a study, researchers sought to validate the decrease in renal GU in individuals with obesity and explore potential associations between circulating metabolites and renal GU.
Eighteen individuals with obesity and 18 nonobese controls underwent [18F]FDG positron emission tomography during insulin clamp. Renal scans were conducted approximately 60 minutes post-[18F]FDG injection. Renal GU was quantified using a fractional uptake rate and adjusted for residual intratubular [18F]FDG. High-throughput proton nuclear magnetic resonance metabolomics assessed circulating metabolites.
Cortical GU was significantly higher in healthy nonobese controls compared to individuals with obesity (4.7 [3.4-5.6] vs. 3.1 [2.2-4.3], P = .004) and positively correlated with insulin sensitivity (M value) (r = 0.42, P = .01). Additionally, cortical GU exhibited inverse associations with circulating β-OH-butyrate (r = -0.58, P = .009), acetoacetate (r = -0.48, P = .008), citrate (r = −0.44, P = .01), and free fatty acids (r = −0.68, P < .0001), independent of the M value. Conversely, medullary GU showed no significant associations with clinical parameters.
The findings confirmed diminished renal cortical GU in individuals with obesity compared to nonobese controls. Moreover, the negative correlations between cortical GU and circulating free fatty acids, ketone bodies, and citrate suggested potential substrate competition within the renal cortex.
Reference: academic.oup.com/jcem/article-abstract/109/4/1033/7416513
