Glycated Haemoglobin and Blood Pressure-Lowering Effect of Cinnamon in Multi-Ethnic Type 2 Diabetic Patients in the UK: A Randomized, Placebo-Controlled, Double-Blind Clinical Trial
Akilen R, Tsiami A, Devendra D, Robinson N
Diab Med. 2010;27:1159-1167
Study Summary
As stated in the title, this relatively small clinical trial used a randomized placebo-controlled, double-blind design to test the effects of daily intake of 2 g of cinnamon on A1C (glycated hemoglobin), blood pressure, and lipid profiles. From 3 sites within the United Kingdom, 58 patients with type 2 diabetes and A1C > 7% on oral antihyperglycemic medication were randomly assigned to receive either cinnamon (n = 30) or placebo (n = 28) for 12 weeks. A1C, fasting glucose, high-density lipoproteins (HDLs), low-density lipoproteins (LDLs), triglycerides, as well as body weight, body mass index and waist circumference were measured at study entry and again at 12 weeks after the intervention.
Patients were 55 years old and most (57%) were Asian/Asian British (Indians/Pakistani/Bangladeshi), while another 26% were black. Although all were receiving oral antihyperglycemics, 76% were on metformin monotherapy, only 34% were receiving antihypertensives, and 33% were taking statins. At baseline, the groups did not differ on any of the clinical measures of interest, with mean A1C of about 8.4% and mean blood pressure of about 133/86 mm Hg. However, after 12 weeks, A1C decreased by 0.36% in the cinnamon group vs a 0.12% increase in the placebo group (P = .002). Changes in systolic (-4 mm Hg vs +1 mm Hg, P < .001) and diastolic (-4 mm Hg vs -1 mm Hg, P < .001) blood pressure also favored the cinnamon group. Nonsignificant differences in body weight (-2.9% vs -0.5%, P = .183) and waist circumference (-2.4 cm vs -0.6 cm, P = .354) were also observed.
Viewpoint
The sale of dietary supplements is a multibillion dollar industry that is mainly comprised of products that have not undergone rigorous scientific testing to validate their effectiveness claims. Patients with diabetes are 1.6 times more likely to use dietary supplements or other forms of complementary and alternative medicine, and a number of products are believed to reduce hyperglycemia. One such product is cinnamon.
Although a previous study found that cinnamon reduced fasting glucose, a meta-analysis of 5 trials did not find a reduction in A1C with cinnamon intake. The apparent A1C and blood pressure benefits reported in the current study were relatively small, the trial was of short duration, and the study population was also somewhat atypical. In any case, it remains to be seen whether these results can be achieved in a more representative sample and sustained over a longer period.
The weight and waist circumference results were interesting but nonsignificant. Perhaps more importantly, the patients in this study appeared to be undertreated. Far more should probably be receiving antihypertensives, especially angiotensin-converting enzyme inhibitors, statins, and a second antihyperglycemic agent as well.
If there is a limit to the number of pills an individual is willing to take, the modest benefits of cinnamon seen in this study do not warrant contributing to that number. However, there does not appear to be any harm in a patient taking cinnamon as long as it does not detract from use of more potent and proven therapies.
Abstract