The SA Journal Diabetes & Vascular Disease Volume 18 No 2 (November 2021)

RESEARCH ARTICLE SA JOURNAL OF DIABETES & VASCULAR DISEASE 22 VOLUME 18 NUMBER 2 • November 2021 RI in patients with DM was due to arteriosclerosis rather than the extensive fibrosis observed in CKD. Elevated renal artery RI is not only associated with the development of nephropathy in patients with DM but was also associated with the progression of kidney disease in those with early stage nephropathy. 33 Reports from other studies have suggested that a Doppler ultrasound scan with the use of intrarenal artery RI makes it possible to diagnose DN earlier than the traditional markers of early kidney damage such as microalbuminuria and eGFR (hyperfiltration). 12-14 The high sensitivity (75.5%) and specificity (92.5%) of RI, coupled with its high positive and negative predictive values of 100 and 81.8%, respectively, suggest a significant role as a screening test for kidney disease in patients with DM. 33 Elevated HbA 1c level was identified as a predictor of high RI among participants with DM without DN. This is in keeping with the findings by El Dayem et al., 33 who reported that elevated HbA 1c level, along with waist–hip ratio, neutrophil gelatinaseassociated lipocalin (NGAL), liver-type fatty acid binding protein (L-FABP) and kidney injury molecule-1 (Kim-1) were associated with elevated intrarenal RI. Persistently elevated HbA 1c level was associated with micro- and macrovascular complications in patients with DM. 34 The impact of uncontrolled DM underscores the need for optimal glycaemic control as an effective means of preventing DN. Unlike Dawha et al., 30 we found no association between age and elevated RI. This finding is surprising as DM accounted for 77% of the deaths in sub-Saharan Africans who were less than 60 years of age, according to the International Diabetes Federation 2017 report. 1 Among patients with DN, hypertension was observed to be associated with elevated RI and this was similar to the findings in the Bruno study, 35 which reported that uncontrolled hypertension was associated with arteriosclerosis and increased intrarenal artery RI among patients with DM with DN and those with DM without DN. Controlling hypertension with agents that reduce intraglomerular pressure such as angiotensin converting enzyme inhibitors (ACEI) and angiotensin receptor blockers (ARB) will not only reduce RI but retards the progression of kidney disease. In this study, the use of ACEI was not associated with elevated RI. 36 This study has demonstrated the utility of Doppler ultrasonography scans using RI in the diagnosis of early kidney disease in patients with DM with DN and those with DM without DN. The measurement of RI has the additional advantage of being non-invasive. Limitations of the study include our inability to assess the effects of elevated RI on the progression of kidney disease among patients with DM with DN and the inability to measure intersegmental RI. In addition, the small sample size and lack of defined and validated reference values in the general population make it difficult to generalise the findings of this study. However, the study employed a design that included three arms of participants with DM with DN, DM without DN and healthy controls, and the use of urinary albumin creatinine ratio and reduced eGFR as markers of kidney injury. Fig. 2. Correlation between RI and urinary albumin–creatinine ratio. Fig. 3. Correlation between RI and estimated eGFR. Fig. 4. Correlation between RI and HbA 1c level.