Diabetic nephropathy in type 2 diabetes mellitus is one of the most serious microvascular complications. Immunoglobulin G (IgG), with molecular weight of 150 kDa, is excreted in urine of normoalbuminuric diabetic patients. Aims The aim was to compare urinary IgG with microalbuminuria as an early indicator of diabetic nephropathy in patients with type 2 diabetes mellitus. Results High significant difference among the different groups was found regarding ACR (P <0.001) and immunoglobulin G creatinine ratio (IgGCR) (P <0.001). ACR and IgGCR are highly increased in groups III and IV in comparison with groups 1 and II. There was a significant positive correlation between IgGCR and age, diabetes mellitus (DM) duration, serum creatinine (P <0.001), blood urea nitrogen, ACR, and renal sonography, and negative correlation with eGFR (P <0.001), hemoglobin, and serum albumin. Conclusion IgG appears in urine in early stages of diabetic nephropathy even before microalbuminuria, so we recommend its use to define high-risk patients, allowing prompt interventions.