Discussion
For the first time in a trial setting, we demonstrated that reducing GI, i.e. changing the type of carbohydrate, reduced markers of kidney function and increased glomerular filtration. Furthermore, this study confirmed prior observations that reducing %carb (i.e. increasing %protein/fat), increases kidney function. Moreover, an increase in eGFRcys from reducing GI tended to have a similar effect as that observed from reducing %carb, and these effects were additive, such that reducing both GI and %carb increased eGFRcys by 4.5 mL/min/ 1.73 m2. The effects persisted after adjustment for potential mediators of kidney function.