Relationship between Intra-renal Resistive Index and Markers of Renal Function Status in Type 2 Diabetic Patients in Southern Nigeria

Background: Diabetes mellitus (DM) is a chronic condition requiring global attention. Renal microangiopathy is a life-threatening microvascular complication often leading to derangements in renal function and progressive renal failure. Renal haemodynamic assessment by duplex Doppler ultrasound scan is a non-invasive method of assessing blood flow resistance within the renal vessels. The intra-renal resistive index (IRI) may be a useful tool in predicting pathological derangements of renal functions in diabetic patients.

Materials and Methods: The study was a cross-sectional study involving 142 consecutive adults with type 2 DM enrolled from December 2017–December 2018. Study approval was obtained from the Ethical and Research Committee of the hospital. Urinalysis, spot urine albumin-to-creatinine ratio (UACR), serum creatinine levels were assessed and glomerular filtration rate estimated using Modification of Diet in Renal Disease equation. All participants had duplex Doppler ultrasound of both kidneys to obtain flow velocities from their interlobar arteries for IRI estimation. Results were analysed with Statistical package for social sciences (SPSS version 23) software.

Results: The study comprised of 87 (61.3%) females and 55 (38.7%) males with a mean age of 55.90±11.02 years. Mean duration of diabetes was 9.60±7.05 years. Mean estimated glomerular filtration rate (eGFR) was 79.18±27.69ml/min/1.73m2, with 31 (21.8%) having their eGFR ≤60mls/min/1.73m2. The mean UACR was 153.65±145.56mg/g with 123 (86.6%) participants having moderate to severe albuminuria The mean average IRI was 0.60±0.09. Participants with diabetic nephropathy (DN) had higher IRI than those without DN (p<0.005). Increased IRI was observed in 36(25.3%) of participants. IRI positively correlated with UACR (p < 0.001) and negatively correlated with eGFR (p < 0.001) and demonstrated a linear relationship with both UACR and eGFR. Increased IRI was associated with duration of diabetes and age.

Conclusion: IRI may be a useful non-invasive tool for early detection and risk prediction of DN.