Combined effect of titanium dioxide nanoparticles and glucose on the blood glucose homeostasis in young rats after oral administration

Titanium dioxide nanoparticles (TiO₂ NPs) were usually consumed with a high content of sugar, and children were identified as having the highest exposures due to sweet food preferences. Research on the combined effect of ingested TiO₂ NPs and glucose has great significance, particularly in young people. We examined young Sprague-Dawley rats administered TiO₂ NPs (0, 2, 10 and 50 mg/kg) orally with and without glucose (1.8 g/kg) for 90 days. Blood glucose homeostasis was assessed by monitoring blood glucose and detecting glycoproteins. Glucose tolerance was also evaluated by the oral glucose tolerance test. The levels of blood glucose-related hormones such as insulin, C-peptide and glucagon were measured. We found that subchronic co-exposure of TiO₂ NPs and glucose caused slight imbalance of blood glucose homeostasis in vivo. Mild and temporary hypoglycemia, impaired glucose tolerance and changes of glucose-regulating hormones were shown in the exposure groups. The combined effect of TiO₂ NPs and glucose was more apparent than that of TiO₂ NPs alone, which may be due to the effects of excess glucose and the interactions between TiO₂ NPs and glucose. The antagonistic effect of TiO₂ NPs with glucose did exist in the level of glycosylated hemoglobin in female rats. Gender differences were apparent in these effects induced by TiO₂ NPs and glucose. Female rats seemed to be more susceptible for blood glucose disorders. Co-exposure of TiO₂ NPs and excessive glucose could induce gender-dependent imbalance of blood glucose homeostasis in rats. It may be the reason that these consumers face greater health risks glycosylated hemoglobin.