Prognostic Nutritional Index as a Marker Associated With Disease Severity in Diabetic Kidney Disease: A Real-World North African Experience

Background: Diabetic kidney disease (DKD) is characterized by chronic inflammation and progressive protein-energy wasting. The Prognostic Nutritional Index (PNI) represents a promising marker for assessing immunonutritional deterioration. Our study aims to evaluate the PNI in patients with type 1 (T1D) and type 2 (T2D) diabetes mellitus with chronic kidney disease (CKD) across all its stages. Materials and methods: A retrospective, cross-sectional analytical study was conducted among patients aged >18 years with T1DM and T2DM, followed between January 2025 and January 2026 at the Department of Endocrinology, Diabetology, and Metabolic Diseases, Hassan II University Hospital, Fez, Morocco. DKD was defined as an albumin-to-creatinine ratio (ACR) >30 mg/g and/or an estimated glomerular filtration rate (eGFR) <90 mL/min/1.73 m2 for ≥3 months. The PNI was calculated using the equation: \(\mathrm{PNI} = \mathrm{Serum\ albumin}\ (\mathrm{g/L}) + 5 \times \mathrm{Lymphocyte\ count}\ (\times 10^{9}/\mathrm{L})\), with PNI ≥50 as normal nutritional status. We stratified patients into three groups: G1: ACR between 30 and 300 mg/g and/or eGFR between 60 and 90 mL/min/1.73 m2; G2: ACR >300 mg/g and/or eGFR <60 mL/min/1.73 m2 (moderate-to-advanced DKD); G3: eGFR <30 mL/min/1.73 m2 regardless of ACR (severe DKD). Exclusion criteria included incomplete medical records, active infection, cirrhosis, cancer, nephrotic syndrome, and chronic inflammatory conditions. Multivariate linear regression was adjusted for demographic factors, diabetes duration, and glycated hemoglobin (HbA1c). Statistical analyses were performed using IBM SPSS Statistics for Windows, Version 26 (Released 2018; IBM Corp., Armonk, New York, United States), with p < 0.05 considered statistically significant. Results: Seventy-eight patients were included (41 T2DM and 37 T1DM). Mean age was 47.3 ± 11.4 years, with female predominance (male-to-female ratio: 0.41). Mean diabetes duration was 23 ± 7.3 years, and mean HbA1c was 11%. Mean PNI was 42.8 in G1 (n = 41), 35.6 in G2 (n = 21), and 28.1 in G3 (n = 16). Multivariate analysis showed a significant deterioration of immunonutritional markers with DKD progression (p < 0.05), with T1DM patients showing more marked kidney function worsening. PNI correlated positively with eGFR (p = 0.002) and inversely with ACR (p = 0.043). In linear regression, eGFR was independently associated with PNI (p = 0.002), and advanced nephropathy stage emerged as the strongest independent predictor of PNI decline (β = -6.47, 95% CI: -11.29 to -1.65, p = 0.011). Conclusion: Immunonutritional status deteriorates progressively with the advancement of DKD. These findings suggest that PNI may represent a useful adjunctive marker of DKD to better identify patients at risk of protein-energy wasting and adverse outcomes.