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The effect of cinnamon extract on insulin resistance in polycystic ovary syndrome: A pilot study

J.G. Wang, R. Anderson, G.S. Nakhuda, M.M. Guarnaccia, M.V. Sauerand R.A. Lobo
^aColumbia Univ, New York, NY; US Dept of Agriculture Beltsville Human Nutrition Research Center, Bethesda, MD.


Available online 30 September 2006.


Objective

Insulin resistance may contribute to the pathogenesis of polycystic ovary syndrome (PCOS). Insulin sensitizing agents have been found to improve insulin resistance and ovulatory dysfunction. Cinnamon extract has been shown to reduce insulin resistance in in vivo and in vitro animal studies by increasing the IRS/PI-3 kinase insulin signaling pathway. We designed this pilot study to test the hypothesis that oral cinnamon extract would improve insulin sensitivity in women with PCOS.

Design

Prospective, randomized, placebo-controlled, double blinded study
Materials and methods

Subjects: 14 women with PCOS (mean BMI 28.8 ± 1.3 kg/m², mean age 31.1±2.0 years) with PCOS according to the 2003 Rotterdam consensus. Protocol: Height and weight were measured to calculate BMI. Transvaginal ultrasound was performed to confirm polycystic appearing ovaries. After a 12 hour fast, fasting bloods were obtained and assayed for glucose, insulin, FSH, LH, prolactin, TSH, testosterone, estradiol, and SHBG by chemoilluminescence. A standard 75 gram oral glucose tolerance test (OGTT) was administered and additional blood samples were taken at 30, 60, and 120 minutes. HOMA-IR, QUICKI, and insulin sensitivity index by the Matsuda method were calculated. Patients were blindly randomized to either the cinnamon extract (1 gram per day) or placebo group. After 8 weeks of treatment, BMI, endocrine parameters, and metabolic parameters were reassessed. Statistical Analysis: Mann-Whitney U tests were used to compare all variables between the placebo and cinnamon groups at baseline. Wilcoxon signed ranks tests were used to compare all variables between baseline and after 8 weeks of treatment in both groups.

Results

In this population of PCOS, there was a mild degree of insulin resistance demonstrated. The placebo and cinnamon groups did not differ with respect to age, BMI, FSH, estradiol, testosterone, fasting glucose, insulin, QUICKI, HOMA-IR, or the insulin sensitivity index. No side effects or adverse reactions were reported in either group throughout the study period. Placebo: There were no changes in BMI, total testosterone, or estradiol. Fasting glucose decreased significantly from 92.57 to 85.43 mg/dl (-7.7%, p<0.03). However, fasting insulin, HOMA-IR, QUICKI, and the insulin sensitivity index remained unchanged. Cinnamon Extract: There were no changes in BMI, total testosterone, or estradiol. Fasting glucose decreased significantly from 95.83 to 79.67 mg/dl (-16.9%, p<0.03). There was a trend towards decreasing fasting insulin from 10.83 to 7.17 μIU/L (-33.8%, p=0.10). QUICKI increased from 0.35 to 0.38 (7.7%, p<0.03) and HOMA-IR decreased from 2.57 to 1.43 (-44.5%, p<0.03) consistent with improved insulin sensitivity. Mean glucose level during OGTT decreased from 144.88 mg/dl per minute to 114.54 mg/dl per minute (-20.9%, p<0.03) and the Matsuda insulin sensitivity index increased from 4.69 to 10.44 (+122.8%, p<0.05).

Conclusion

8 weeks of treatment with cinnamon extract significantly decreased fasting glucose and improved insulin resistance as measured by HOMA-IR, QUICKI, and the insulin sensitivity index. No significant changes in these indices were found in the placebo group. Large scale prospective studies are needed to confirm these preliminary findings.


Article was found through Science Direct.