Plasma levels and dietary intake of minerals in patients with type 2 diabetes and chronic kidney disease

Abstract

Diabetic kidney disease (DKD) is the primary cause of chronic kidney disease (CKD) worldwide. Altered mineral levels leading to adverse outcomes are widely reported in diabetes, but studies regarding their status in DKD are limited. To explore the status of minerals, a hospital-based case-control study was taken up with 54 healthy controls (C) and 140 subjects with type 2 diabetes wherein 74 subjects with diabetes, and CKD formed the DKD group, and 66 subjects with diabetes, no CKD formed the DNCKD group. High-resolution inductively coupled plasma mass spectrometry was used to evaluate the blood levels of minerals (Ca, V, Cr, Mn, Fe, Co, Cu, Zn, and Se), and raw food-based food frequency questionnaire for dietary intakes. The median values of plasma Ca in the DKD group were significantly lower compared with the DNCKD and C groups (10.5 mg/dL vs. 11.0 mg/dL and 11.7 mg/dL, p < 0.001). Furthermore, plasma Ca levels lowered with declining kidney function, as evidenced by the estimated glomerular filtration rate (eGFR) and albuminuria segregation. Dietary intake of minerals did not correlate with the corresponding plasma levels. However, in the DKD group, eGFR correlated positively with the plasma levels of Ca (r = 0.422, p = 0.001), Cr (r = 0.351, p = 0.008), Mn (r = 0.338, p = 0.011), Fe (r = 0.403, p = 0.002), Cu (r = 0.274, p = 0.041) and negatively with Se (r= -0.486, p < 0.001). Plasma Ca levels are lower in the DKD group with a strong positive association with eGFR, indicating its role in predicting the onset and progression of kidney function decline.