Can long-term exposure to chromium improve insulin sensitivity in chromium mine workers?

The purpose of this work was to evaluate insulin sensitivity in chromium mine workers exposed to chromium chronically. Body mass index, waist circumference, fat mass and percent, lipid levels, serum glucose, insulin, leptin and chromium levels, HOMA (%S), and HOMA (%B) values were measured in 93 male workers and 94 age- and body mass index-matched healthy controls. Fat mass and fat percent of workers were higher than control subjects (P < 0;01 and P < 0.0001, respectively). Mean insulin level of the workers was lower than control subjects (6.2 +/- 4.9 muU/mL and 9.38 +/- 5, respectively, P < 0.0001). Mean serum leptin levels was also lower than the control group (8.47 +/- 6.5 ng/mL and 19.0 +/- 10.8, respectively, P < 0.0001). Serum chromium was higher than the control subjects (407.7 +/- 224.2 nmol/L and 4.45 +/- 3.9, respectively, P < 0.00001). Mean HOMA (%S) index of workers was higher than control subjects (114.4 +/- 55.6 and 55.7 +/- 40.6, P < 0.001). Serum high-density lipoprotein cholesterol levels of the workers were significantly higher than the control group (P < 0.02). In conclusion, long-term exposure to chromium may improve insulin sensitivity and beta-cell function. This improvement appears to be a result of low body fat mass and fat percent in body composition. In addition chromium usage may have useful effects in the insulin sensitivity and therefore in development of type 2 diabetes mellitus.