Glucose and insulin responses to dietary chromium supplements: a meta-analysis.
BACKGROUND
Several authors, mostly on the basis of nonrandomized studies, have suggested dietary trivalent chromium supplementation as an attractive option for the management of type 2 diabetes and for glycemic control in persons at high risk of type 2 diabetes.


OBJECTIVE
The study aimed to determine the effect of chromium on glucose and insulin responses in healthy subjects and in individuals with glucose intolerance or type 2 diabetes.


METHODS
The study design was a systematic review and meta-analysis of randomized clinical trials (RCTs).


RESULTS
The authors identified 20 reports of RCTs assessing the effect of chromium on glucose, insulin, or glycated hemoglobin (Hb A(1c)). This review summarizes data on 618 participants from the 15 trials that reported adequate data: 193 participants had type 2 diabetes and 425 were in good health or had impaired glucose tolerance. The meta-analysis showed no association between chromium and glucose or insulin concentrations among nondiabetic subjects. A study of 155 diabetic subjects in China showed that chromium reduced glucose and insulin concentrations; the combined data from the 38 diabetic subjects in the other studies did not. Three trials reported data on Hb A(1c): one study each of persons with type 2 diabetes, persons with impaired glucose tolerance, and healthy subjects. The study of diabetic subjects in China was the only one to report that chromium significantly reduced Hb A(1c).


CONCLUSIONS
Data from RCTs show no effect of chromium on glucose or insulin concentrations in nondiabetic subjects. The data for persons with diabetes are inconclusive. RCTs in well-characterized, at-risk populations are necessary to determine the effects of chromium on glucose, insulin, and Hb A(1c).
Althuis
Michelle D
MD
Statistics Collaborative, Inc, Washington, DC, USA. althuism@mail.nih.gov
Jordan
Nicole E
NE
Ludington
Elizabeth A
EA
Wittes
Janet T
JT
D001786:Blood Glucose / Q000378:metabolism*; D002857:Chromium / Q000008:administration & dosage* / Q000627:therapeutic use; D018592:Cross-Over Studies; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000188:drug therapy; D019587:Dietary Supplements; D005215:Fasting; D018149:Glucose Intolerance / Q000097:blood; D005951:Glucose Tolerance Test; D006442:Glycated Hemoglobin / Q000032:analysis; D006801:Humans; D007328:Insulin / Q000097:blood*; D016239:MEDLINE; D010919:Placebos; D016032:Randomized Controlled Trials as Topic
D001786:Blood Glucose; D002857:Chromium; D006442:Glycated Hemoglobin; D007328:Insulin; D010919:Placebos