An Evidence-Based Approach to Vitamins and Minerals: Health Benefits and Intake Recommendations by Jane Higdon & Victoria Drake

Author:Jane Higdon & Victoria Drake [Higdon, Jane]
Language: eng
Format: epub, mobi
Publisher: Thieme Medical Pub
Published: 2011-09-06T22:00:00+00:00

Type 2 Diabetes Mellitus

Type 2 diabetes is characterized by elevated blood glucose levels and insulin resistance. Although insulin levels in people with type 2 diabetes may be higher than in healthy individuals, the physiological effects of insulin are reduced. As chromium is known to enhance the action of insulin, the relationship between chromium nutritional status and type 2 diabetes has generated considerable scientific interest. Individuals with type 2 diabetes have been found to have higher rates of urinary chromium loss than healthy individuals, especially those with diabetes of more than 2 years’ duration.21 Before 1997, well-designed studies of chromium supplementation in individuals with type 2 diabetes showed no improvement in blood glucose control, although they provided some evidence of reduced insulin levels and improved blood lipid profiles.22

In 1997, the results of a placebo-controlled trial conducted in China indicated that chromium supplementation might be beneficial in the treatment of type 2 diabetes;23 180 participants took either a placebo or chromium in the form of chromium picolinate at doses of 200 µg/day and 1000 µg/day. At the end of 4 months, blood glucose levels were 15%–19% lower in those who took 1000 µg/day compared with those who took the placebo. Blood glucose levels in those taking 200 µg/day did not differ significantly from those who took placebo. Insulin levels were lower in those who took either 200 µg/day or 1000 µg/day of chromium picolinate. Glycated hemoglobin levels, a measure of long-term control of blood glucose, were also lower in both chromium-supplemented groups, especially in the group taking 1000 µg/day. As the chromium nutritional status of the Chinese participants had not been evaluated and the prevalence of obesity was much lower than is typically associated with type 2 diabetics in the United States, extrapolation of these results to a US population is difficult. There have been subsequent studies investigating the utility of chromium picolinate for the treatment of type 2 diabetes.

A recent review reported that 13 of 15 clinical studies, including the study conducted in China, found that chromium picolinate improved at least one measure of glycemic control in diabetic patients.24 Chromium picolinate is more bio-available than other supplemental forms of chromium and therefore may be more efficacious. However, large-scale randomized controlled trials of chromium supplementation for type 2 diabetes are needed to determine if chromium is effective in its treatment.

Gestational Diabetes

Few studies have examined the effects of chromium supplementation on gestational diabetes. Gestational diabetes occurs in about 2% of pregnant women and usually appears in the second or third trimester of pregnancy. Blood glucose levels must be tightly controlled to prevent adverse effects on the developing fetus. After delivery, glucose tolerance generally reverts to normal. However, 30%–40% of women who have had gestational diabetes develop type 2 diabetes within 5–10 years. An observational study in pregnant women did not find serum chromium levels to be associated with measures of glucose tolerance or insulin resistance in late pregnancy, although serum chromium levels may not reflect tissue chromium levels.25 Women with gestational diabetes whose

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