['We evaluated the relationship between the HO1 genotype, ferritin levels and the risk of type-2 diabetes and inflammation.', 'Eight hundred thirty-five individuals were evaluated and classified according to their nutritional status and the presence of type-2 diabetes: 153 overweight (OW); 62 obese (OB); 55 type-2 diabetes mellitus (DM); 202 OWDM; 239 OBDM and 124 controls (C). We studied biochemical (glycemia, insulin, lipid profile, liver enzyme, creatinine, hsCRP), hematological (hemoglobin, free erythrocyte protoporphyrin, transferrin receptor and serum Fe and ferritin) and oxidative stress (SOD, GHS and TBARS) parameters. We determined heme oxygenase activity and the (GT)n polymorphism in its gene promoter.', 'Individuals with diabetes, independent of nutritional status, showed high levels of ferritin and HO activity compared to control subjects. Allelic frequency was not different between the groups (Chi(2), NS) however, genotypes were different (Chi(2), P<0.001). The SS (short-short) genotype was higher in all DM individuals compared to controls and MM was higher in controls. SM (short-medium) genotype was an independent risk factor for DM in logistic regression analysis. We observed high risk for type-2 diabetes mellitus in the presence of SM genotype and high levels of ferritin (OR adjusted: 2.7; 1.9-3.6; p<0.001; compared to control group). It was also significantly related to inflammation.'] Is short repeats in the heme oxygenase 1 gene promoter associated with increased levels of inflammation , ferritin and higher risk of type-2 diabetes mellitus?