I am unaware of any study linking Agent Orange to kidney disease. The Veterans Administration has studied this issue extensively and has recognized certain illnesses that they can link to exposure to Agent Orange. Diabetes has been linked to exposure to Agent Orange. You can review a list of the diseases linked to Agent Orange at the VA web site: https://www.va.gov/disability/eligibility/hazardous-materials-exposure/agent-orange/related-diseases/
You are correct that diabetes is clearly linked to chronic kidney disease (CKD). I am unable to offer you any information about a direct link for Agent Orange and CKD.