Fig. 1

Separate lung exposure to air pollution particles does not induce diabetes, while gut exposure induces glucose intolerance and impaired insulin secretion in mice fed a standard diet. A Schematic illustration of lung exposure model. Wild-type mice were intratracheally instilled with 30 µg diesel exhaust particles (DEP), particulate matter (PM) or PBS twice weekly starting at 5–6 weeks of age for 6 months. B Time course of glucose tolerance tests (GTT) for months 3–5. C Body weight over time. D Insulin, body weight and fasting glucose after 5 months of exposure. E Schematic illustration of gut exposure model. Wild-type mice were treated with 12 µg diesel exhaust particles (DEP), particulate matter (PM) or PBS 5 times per week via gavage starting at 5–6 weeks of age for up to 6 months. F Time course of glucose tolerance tests (GTT) for months 3–5. G Body weight over time. H Insulin, body weight and fasting glucose after 4 months of gavage. I ITT after 3 months of treatment. Data are presented as mean ± SEM of 5 mice per group from one representative experiment. GTT and insulin values were compared by two-way ANOVA, body weight and fasting glucose by a two-tailed, unpaired Mann–Whitney U test (*p < 0.05, **p < 0.01). * indicates significances between 12 µg DEP and PBS controls and & between 12 µg PM and PBS controls