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

SA JOURNAL OF DIABETES & VASCULAR DISEASE RESEARCH ARTICLE VOLUME 18 NUMBER 2 • November 2021 21 of low RIs between subjects with DM with DN and those with DM without DN, while there were significant differences individually between the subjects with DM with DN, those with DM without DN and the controls (Table 4). Factors associated with elevated RI among participants with DM without DN included elevated HbA 1c level [odds ratio (OR) 4.22; 95% confidence interval (CI): 1.0017–17.7962, p = 0.04] and dyslipidaemia (OR 5.38, 95% CI: 1.1201–29.3440, p = 0.04) (Table 5), while only HbA 1c level independently predicted high RI among participants with DM without DN on logistic regression analysis (OR 2.81; 95% CI: 1.7256–9.0287, p = 0.02). The duration of DM greater than five years (OR 1.30; 95% CI: 0.4363–3.8733) and hypertension (OR 3.60; 95% CI: 1.0604– 12.2216, p = 0.04) (Table 6) were factors associated with elevated RI in participants with DM with DN. Hypertension independently predicted high RI in participants with DM and DN following logistic regression analysis. We observed no relationship between RI and UACR ( r = 0.274) (Fig. 2), while there was an inverse correlation between RI and eGFR ( r = –192) (Fig. 3). There was a direct correlation between HbA 1c level and RI but it was not statistically significant (r = –0.179, p = 0.084) (Fig. 4). Discussion Our study showed a high prevalence of elevated RI among participants with DM without DN and those with DM with DN. Elevated HbA 1c levels and hypertension were found to predict the occurrence of elevated RI in the participants with DM without DN and those with DM with DN, respectively. The mean ages of the participants across the three arms of the study were in the mid-range, which is similar to the age ranges that have been reported among patients with type 2 DM and those with DN. 30 The highest prevalence of RI was observed among participants with DN. The prevalence of 43.4% was similar to reports from other studies among patients with DN. Raut et al. 19 reported an elevated RI at a prevalence of 55% among patients with DN while Milovanceva-Popovska et al. 31 reported a prevalence of 40% of elevated RI among patients with DN. In this study, elevated RI was higher among participants with DM with DN compared to those with DM without DN. The prevalence of elevated RI in the participants with DM without DN in our study is similar to that observed by Afsar et al. ,32 who reported a prevalence of 23.8%. The increased intrarenal artery RI in DM patients was not unexpected, because the loss of glomerular capillaries from endothelial dysfunction and vascular damage that occurs in uncontrolled DM causes subsequent reduction in the cross-sectional area of renal vessels over time. It has been suggested that the high Table 3. Comparison of the RI among the three study arms DM DM Healthy without DN with DN controls [mean ± SD/ [mean ± SD/ [mean ± SD/ frequency frequency frequency (%)] (%)] (%)] Variables ( n = 40) ( n = 53) ( n = 40) p -value Right interlobar 0.58 ± 0.05 0.61 ± 0.05 0.54 ± 0.04 0.04 artery RI Left interlobar 0.56 ± 0.05 0.56 ± 0.05 0.54 ± 0.04 0.17 artery RI Mean of both right 0.60 ± 0.04 0.61 ± 0.04 0.56 ± 0.04 0.02 and left interlobar arteries RI Elevated RI 12 (30.0) 23 (43.4) 5 (12.5) 0.01 RI: resistivity index; DM: diabetes mellitus; DN: diabetic nephropathy. Table 4. Post hoc analysis among the three groups for mean and low RI RI [mean ± SD/ Variables frequency (%)] p -value DM with DN versus DM without DN DM with DN 0.61 ± 0.04 0.69 DM without DN 0.60 ± 0.04 Low RI DM with DN 23 (43.4) 0.18 DM without DN 12 (30) DM with DN versus controls DM with DN 0.61 ± 0.05 0.03 Healthy controls 0.56 ± 0.04 Low RI DM with DN 23 (43.4) 0.01 Healthy controls 5 (12.5) DM without DN versus controls DM with DN 0.60 ± 0.04 0.04 Healthy controls 0.56 ± 0.04 Low RI DM without DN 12 (30) 0.06 Healthy controls 5 (12.5) RI: resistivity index; DM: diabetes mellitus; DN: diabetic nephropathy. Table 5. Factors associated with high RI among DM patients with DN Elevated RI Normal RI [frequency [frequency (%)] (%)] Variables ( n = 12) ( n = 28) Odds ratio (95% CI) p -value Age ≥ 65 years 8 (66.7) 15 (53.6) 1.73 (0.4213–7.0011) 0.44 Gender (male) 7 (58.3) 12 (42.9) 1.87 (0.4743–7.3472) 0.66 Duration of DM 9 (75) 13 (48.4) 3.46 (0.7701–5.5601) 0.09 (> 5 years) Hypertension 7 (58.3) 12 (42.7) 1.86 (0.4743–7.3472) 0.37 Use of antihypertensives 4 (33.3) 11 (39.3) 0.77 (0.1868–3.1962) 0.72 Use of ACEI 3 (25.0) 9 (32.1) 0.70 (0.1626–3.2451) 0.65 Elevated HbA 1c 8 (66.7) 9 (32.1) 4.22 (1 .0017–17.7962) 0.04 Dyslipidaemia 10 (88.3) 13 (48.2) 5.38 (1.1201–29.3440) 0.03 ACEI: angiotensin converting enzyme inhibitor; DM: diabetes mellitus; HbA 1c : glycated haemoglobin; RI: resistivity index; CI: confidence interval. Table 6. Factors associated with high RI among DM patients with DN Elevated RI Normal RI [frequency [frequency (%)] (%)] Variables ( n = 23) ( n = 30) Odds ratio (95% CI) p -value Age ≥ 65 years 9 (39.1) 17 (56.7) 0.49 (0.1627–1.4854) 0.20 Gender (male) 4 (17.4) 7 (23.3) 0.69 (0.1757–2.7237) 0.59 Duration of DM 11 (60.9) 14 (33.3) 3.11 (1 .0047–9.6334) 0.04 (< 5 years) Hypertension 18 (78.3) 15 (50.0) 3.60 (1.0604–12.2216) 0.04 Use of 11 (47.8) 12 (40.0) 1.38 (0.4592–4.1174) 0.33 antihypertensives Use of ACEI 9 (39.1) 8 (22.7) 1.77 (0.5517–5.6648) 0.34 Elevated HbA 1c 9 (39.1) 5 (16.7) 3.21 (0.8990–11.4822) 0.07 Dyslipidaemia 13 (56.5) 15 (50.0) 1.30 (0.4363–3.8733) 0.61 ACEI: angiotensin converting enzyme inhibitor, DM: diabetes mellitus, HbA 1c : glycated haemoglobin; RI: resistivity index; CI: confidence interval.