Peri-renal and renal sinus fat accumulation and diabetic kidney disease in type 2 diabetes: A Japanese cohort study.

Over a median 8.5-year follow-up, 53.7% of participants with type 2 diabetes developed diabetic kidney disease.

• Study enrolled 190 DKD-free individuals with type 2 diabetes at baseline.
• Median follow-up duration was 8.5 years.
• 53.7% of patients developed DKD during the follow-up period.
• This was a 15-year cohort study conducted in a Japanese population.

Higher RSFVI tertiles were significantly associated with increased DKD risk.

• Hazard ratio for higher RSFVI tertiles was 1.96 (95% confidence interval 1.14–3.39, P=0.016).
• The association was independent of conventional DKD risk variables.
• RSFVI tertiles were used to categorize participants for analysis.
• This association persisted after adjustment for standard risk factors.

RSFVI had the best predictive value for DKD development among all five adiposity indices examined.

• AUC for RSFVI was 0.769, the highest among all indices tested.
• The five adiposity indices compared were BMI, visceral fat area (VFA), subcutaneous fat area (SFA), PRFVI, and RSFVI.
• Both renal fat indices (PRFVI and RSFVI) showed stronger associations with DKD development than traditional obesity measures.
• RSFVI provided incremental predictive value beyond conventional DKD risk variables.

PRFVI and RSFVI had distinct correlates, with PRFVI correlating with BMI and RSFVI correlating with aging.

• PRFVI was correlated with BMI, suggesting it tracks general adiposity.
• RSFVI was correlated with aging, suggesting a distinct biological pathway.
• These differential correlations indicate that peri-renal and renal sinus fat depots have different determinants.
• The distinction may explain why RSFVI independently predicts DKD beyond general obesity measures.

The study population consisted of Japanese adults with type 2 diabetes who were relatively non-obese at baseline.

• Participants averaged 58 years old.
• 52.6% were male.
• Median diabetes duration was 5 years.
• Mean BMI was 25.4 kg/m², indicating a non-obese cohort by conventional Western standards.
• All 190 participants were free of DKD at baseline.

Renal fat was measured using computed tomography and categorized into peri-renal fat volume index and renal sinus fat volume index.

• Abdominal and renal fat were measured via computed tomography (CT).
• Participants were categorized into tertiles based on five adiposity indices: BMI, VFA, SFA, PRFVI, and RSFVI.
• PRFVI refers to peri-renal fat volume index and RSFVI refers to renal sinus fat volume index.
• CT-based measurement allowed quantification of distinct regional fat depots around the kidney.