CD79A and diabetes mellitus: Renal biopsy maybe indicated to establish the correct diagnosis and to ascertain the severity of glomerular and tubulointerstitial pathology.<h4>Case</h4>We report a patient with type 2 diabetes mellitus and chronic renal insufficiency who developed worsening of renal function in the setting of staphylococcal infection and antibiotic use.<h4>Conclusion</h4>Renal biopsy revealed IgA-dominant post-infectious glomerulonephritis and acute interstitial nephritis superimposed on diabetic glomerulosclerosis.