Effects of dietary inorganic trivalent chromium (Cr3+) on the development of glucose homeostasis in rats.

Inorganic chromium (Cr3+) is classified as an essential trace element on the basis of a small dietary requirement for the maintenance of efficient glucose homeostasis. The present study has carefully scrutinised this claim by examining food intake, body weight gain, glycosylated haemoglobins, plasma glucose and insulin concentrations, glucose tolerance and insulin sensitivity in two groups of Wistar rats fed either a Cr3+-deficient (0.03 mg/kg) or Cr3+-containing (1 mg/kg) diet for 32 days from weaning at 3 weeks. At 53 days of age, control rats weighed 183 +/- 7 g (body weight gain 155 +/- 6 g, mean +/- SEM) and consumed 17 +/- 1 g diet/rat/day. Glycosylated haemoglobins, plasma glucose and plasma insulin were 2.5 +/- 1%, 6.4 +/- 0.3 mmol/l and 1.2 +/- 0.3 ng/ml, respectively. Compared with control rats, the rats fed the Cr3+-deficient diet consumed the same total amount of diet and exhibited up to a maximum 40% decrease in the chromium content of selected tissues at 53 days of age. At no time during the study did food intake, body weight, glycosylated haemoglobins or plasma concentrations of glucose and insulin differ between the two groups of rats. Furthermore, body weight gain and both glucose tolerance and insulin sensitivity were identical at 50-53 days of age. These results cast doubt on the significance of dietary trivalent chromium for the maintenance of glucose homeostasis in healthy animals.