Predictors of One-Year Renal Function Decline in Type 2 Diabetes: Implications for Metabolic Target Management

<b>Background</b>: Early decline in kidney function is a major complication of type 2 diabetes mellitus (T2DM). The extent to which achievement of glycemic, blood pressure, lipid, and weight targets influences short-term renal trajectories remains insufficiently characterized. <b>Methods</b>: We conducted a retrospective analysis of 125 T2DM patients who had baseline and 1-year follow-up eGFR measurements at the Mongolia Japan Hospital of the MNUMS during 2023-2024. Clinical and metabolic control was categorized using standard thresholds. Renal outcomes were assessed using absolute 1-year eGFR change and the occurrence of ≥30% decline. <b>Results</b>: Mean eGFR declined from 91.2 ± 24.1 to 88.4 ± 25.5 mL/min/1.73 m² over one year (mean change -3.77 ± 11.3 mL/min/1.73 m²); 7.2% experienced ≥30% decline. Individuals with pre-existing CKD showed significantly greater deterioration than those without (interaction <i>p</i> < 0.001). Poor glycemic control was consistently associated with greater decline: participants with HbA1c > 7.5% had a significant reduction and regression analyses showed an additional adjusted decline of -4.7 mL/min/1.73 m² (<i>p</i> = 0.029) compared with those at target. Elevated blood pressure (>130/80 mmHg) was also associated with greater annual decline (adjusted β = -6.40, <i>p</i> = 0.024). Lower BMI (<25 kg/m²) predicted larger decreases in eGFR in both CKD and non-CKD groups. Lipid target achievement demonstrated small, inconsistent associations with renal outcomes. <b>Conclusions</b>: In this clinical cohort, poor glycemic control and elevated blood pressure were the strongest modifiable predictors of short-term kidney function decline, particularly among individuals without pre-existing CKD.