Type 2 diabetes albuminuric and non-albuminuric phenotypes have different morphological and functional ultrasound features of diabetic kidney disease

Aims Whether different diabetic kidney disease (DKD) phenotypes recognise differences in morphological and vascular properties of the kidney is still unexplored. We evaluated the potential role of kidney ultrasonography in differentiating DKD phenotypes in subjects with type 2 diabetes. Materials and Methods This is a cross-sectional, single-centre study. Total (TRV) and parenchymal renal volumes (PRV) were calculated by applying the ellipsoid formula for conventional (2D) ultrasonography and with manual segmentation for 3D ultrasonography, and then adjusted for body surface area (aTRV, aPRV). Renal resistive index (RI) was contextually determined. DKD phenotypes have been defined based on increased urinary albumin-to-creatinine ratio (ACR >30 mg/g) and/or reduced eGFR (<60 ml/min/1.73 m(2)). Recruitment was planned to have groups of the same size. Results Among 256 subjects, 26.2% had No-DKD, 24.6% increased albuminuria only (Alb(+)), 24.2% non-albuminuric DKD (Alb(-)DKD), and 25.0% albuminuric DKD (Alb(+)DKD). Compared to No-DKD, RI was significantly higher in all DKD phenotypes, being the highest in Alb(+)DKD, and with a significant trend of RI > 0.70 to increase across phenotypes. In comparison with No-DKD, both 2D and 3D volumes were increased in Alb(+) and significantly reduced in Alb(-)DKD as well as in Alb(+)DKD, with significantly lower volumes in Alb(-)DKD as compared to Alb(+)DKD at the same reduced levels of eGFR. In adjusted regressions, compared to No-DKD, RI was associated with Alb(+); both RI and aPRV3D were associated with Alb(+)DKD; only aPRV3D with Alb(-)DKD. Compared to No-DKD, Receiver Operating Characteristic curve analyses, designed taking into account conventional risk factors, showed that US parameters did not ameliorate the characterisation of Alb(+) and Alb(+)DKD, while aPRV3D significantly improved the phenotyping of Alb(-)DKD. Conclusions As a novel information, we reported that, in type 2 diabetes, the emerging normoalbuminuric DKD phenotype showed reduced TRVs and PRVs even when compared, at similarly reduced eGFR levels, with Alb(+)DKD opening. In perspective, these findings suggest a possible role of imaging for better discrimination of DKD phenotypes in clinical practice.