Aim: An analysis is made of the saliva and plasma levels of trace elements in patients with type 2 diabetes mellitus and their association to metabolic control and the presence of chronic complications. Methods: A cross-sectional observational clinical study was carried out in 74 patients with type 2 diabetes mellitus. Mass spectrometry (ICP-MS) was used to determine the following trace elements in plasma and unstimulated basal saliva: Al-33, S-16, Be-4, B-5, (20)ca, Co-27, Cu-29, Cr-24, Sr-38, P-15, Li-3, Mg-12, Mn-28, Ni-28, Pb-82, Pb-32, Ti-22, V-23 and Zn-30. Results: The levels of cobalt (p = 0.048) in saliva and of strontium (p = 0.001) in plasma were related to the presence of chronic complications. Significant differences with respect to metabolic control were observed for beryllium (p = 0.038), boron (p = 0.023) and phosphorus in saliva (p = 0.046), and for rubidium (p = 0.005), titanium (p = 0.016) and zinc in plasma (p = 0.013). A significant correlation (p < 0.001) was found between boron in plasma and boron in unstimulated basal saliva. Conclusions: The determination of trace elements in plasma and saliva constitutes a complementary tool for the assessment of metabolic control and for predicting chronic complications associated to type 2 diabetes mellitus. Further studies involving the biomonitoring of trace elements in saliva and plasma are needed. (C) 2019 Elsevier B.V. All rights reserved.