Objectives: A classic type of diabetic kidney disease is known to have natural courses of initiation of glomerular hyperfiltration and microalbuminuria, followed by macroalbuminuria, then a decrease in glomerular filtration rate. However, recently, a new form of diabetic kidney disease, which is associated with reduced renal function without proteinuria, is widely accepted. The extent of the degree to how diabetes negatively affects renal function in this new form of kidney disease is not well studied. Methods: We analyzed data from National Health Insurance Service-National Sample Cohort in Korea (2009–2015). The patients who had normal baseline eGFR levels and those who had negative urine dipsticks in baseline and follow-up measurements were involved.  Results: Among a total of 587,339 patients with health examination results in NHIS-NSC during 2009–2015, 77,267 patients were eligible for analysis (diabetics, 11,957 vs. non-diabetics, 65,310). Figure 1 shows that diabetic group had more decline in annual declines of eGFR (-0.113 [-0.222, -0.003], in a linear mixed-model adjusted for other confounding factors). The steeper decline in eGFR was highlighted in patients with glomerular hyperfiltration and longer durations of diabetes (Figure 2). Conclusions: Our study showed that diabetes has 1.5 times of increased risk of negative effect on renal outcome in diabetic patients with normal renal function compared to non-diabetic those with normal renal function. Additionally, longer durations of diabetes and glomerular hyperfiltration have additional negative effects on renal function in diabetic patients with normal renal function.