Studies conflict on use of cinnamon to treat type 2 diabetes

Integrative Medicine

Almost 26 million Americans have diabetes, and an additional 73 million adults have prediabetes. Most people in the latter group remain undiagnosed. The optimal management of diabetes, especially for type 2, requires addressing not only glucose concentrations but also concomitant lipid and blood pressure measures. Fortunately, multiple drug therapies are available to improve diabetes management and lessen the risk of long-term complications such as cardiovascular and renal disease.

Many patients with diabetes are also interested in using complementary approaches for managing their disease, such as the supplements chromium, zinc, magnesium, fenugreek, garlic, ginseng, gymnema, and cinnamon. For the past 10 years, many patients with diabetes have been particularly interested in using cinnamon to lower blood glucose concentrations. This interest was first sparked by a 2003 Pakistani study of 60 patients with type 2 diabetes.1 The patients had significant improvements in fasting glucose concentrations, as well as lipid concentrations, while taking cinnamon in dosages of 1 g to 6 g daily.

The potential active ingredient of cinnamon is cinnamaldehyde, which has been proposed to improve insulin sensitivity, among other effects. In the years since this initial report, multiple additional small studies have provided conflicting results on the potential benefits of cinnamon.

Meta-analyses

A 2013 meta-analysis in Annals of Family Medicine presented an updated review of the available evidence on the use of cinnamon in type 2 diabetes.2 The study reported that fasting glucose concentrations were reduced by almost 25 mg/dL using dosages ranging from 120 mg to 6 g daily for periods between 4 weeks and 18 weeks. Similarly, total cholesterol, LDL cholesterol, and triglyceride concentrations were decreased by 15.6 mg/dL, 9.4 mg/dL, and 29.6 mg/dL, respectively. The HDL cholesterol values were increased by 1.66 mg/dL. Hemoglobin A1C reflecting longer-term diabetic control was unchanged.

Although some findings appear to be impressive, considerable variation exists between studies when reviewing the individual outcome data. In addition, some studies were from countries with dietary patterns that are significantly different from those of most Americans with type 2 diabetes. In addition to the effects of cinnamon on glucose and lipid concentrations, a 2013 meta-analysis in Nutrition identified three small studies published between 2000 and 2012 that evaluated the supplement’s effects on blood pressure.3 The studies used either a controlled parallel or crossover design along with a specified dosage of cinnamon. The studies also measured blood pressure at baseline prior to cinnamon treatment.

A total of 139 individuals were in the meta-analysis. Study participants had a body mass index ranging from 29.8 kg/m2 to 34.4 kg/m2. The dosage of cinnamon ranged from 500 mg to 2.4 g per day, and the studies had an average duration of 12 weeks. The participants were middle aged, and their mean age varied by almost 20 years in the three studies. Cinnamon use lowered systolic blood pressure by 5.39 mm Hg and diastolic blood pressure by 2.6 mm Hg.

What to tell patients

Nutritional approaches are the foundation of maintaining overall good health in patients with and without diabetes. For patients with type 2 diabetes, weight loss through diet and exercise is one of the best ways to control blood glucose and lipids as well as blood pressure. Although cinnamon is a generally safe dietary supplement, its effects on glucose, lipids, and blood pressure in type 2 diabetes are modest at best. The evidence of its short-term benefits is from populations whose diets may differ substantially from those of the typical American with type 2 diabetes. Most importantly, because its long-term benefits are unknown, use of cinnamon does not replace standard therapies such as metformin, statins, and lisinopril.

References

  1. Diabetes Care. 2003;26(12):3215–8.
  2. Ann Fam Med. 2013;11(5):452–9.
  3. Nutrition. 2013;29(10):1192–6.