Table 1. Baseline characteristics, interventions, and outcomes of included trials.

BD - twice a day; TDS - three times daily; FBG - fasting blood glucose; HbA1C - glycosylated hemoglobin; HDL - high-density lipoprotein; LDL - low-density lipoprotein

Study (Author, Year, Area)	Participants (Type 2 diabetic adult people divided into groups)	Treatment/Control/Placebo	Duration	Outcome
Khan A, 2003, Pakistan [6]	Cinnamon group - 10; Placebo group - 10	C. cassia bark powder 500 mg capsule BD. Placebo - wheat flour 500 mg capsule BD.	40 days	Significant (p<0.05) reduction had been seen in the level of fasting blood glucose, triglyceride, total cholesterol, and LDL cholesterol. Non-significant (p>0.05) changes were found in the HDL cholesterol level.
Vanschoonbeek K, 2006, Netherlands [7]	Cinnamon group - 12; Placebo group - 13	C. cassia bark powder 500 mg capsule TDS. Placebo - not specified 500 mg capsule TDS.	6 weeks	There was no time× treatment interaction for fasting blood glucose, HbA1C, triglycerides, total cholesterol, and LDL and HDL cholesterol (p>0.05).
Blevins SM, 2007, USA [8]	Cinnamon group - 29; Placebo group - 28. Intention to treat analysis was used.	C. cassia bark powder 500 mg capsule BD. Placebo - wheat flour 500 mg capsule BD.	90 days/3 months	Non- significant results had been found (significance was set at 0.05). Values of outcome variable were FBG (p= 0.38); HbA1C (p= 0.64); triglyceride (p= 0.78); total cholesterol (p= 0.63); LDL (p=0.87); HDL (p= 0.28).
Crawford P, 2009, USA [9]	Cinnamon group - 55; Placebo group - 54. Intention to treat analysis was used.	Usual care with C. cassia bark powder capsules 500 mg BD. Control - Usual care alone.	90 days	There was a significant decrease of HbA1C (p<0.04) among the intervention group.
Akilen R, 2010, UK [10]	Cinnamon group - 30; Placebo group - 28. Intention to treat analysis was used.	C. cassia bark powder 500 mg capsule four times per day. Placebo - Starch powder 500 mg capsule 4 times per day.	12 weeks	Intake of cinnamon significantly reduced HbA1C (p= 0.029) when comparing the post-intervention mean of cinnamon and placebo group. The changes in fasting plasma glucose and lipid profiles were not significantly different from placebo (p>0.05).
Hasanzade F, 2013, Iran [11]	Cinnamon group - 35; Placebo group - 35.	C. cassia bark powder 500 mg capsule BD. Placebo - not specified 500 mg capsule BD.	60 days	There was no significant change in the level of FBG and HbA1C between the two groups after the intervention (P > 0.05).
Mirfeizi M, 2015, Iran [12]	Cinnamon group - 27; Placebo group - 45.	C. cassia bark powder 500 mg capsule BD. Placebo - starch 500 mg capsule BD.	90 days/3 month	Non- significant changes was found in the level of FBG (p=0.172); HbA1C (p=0.284); triglyceride (p=0.168); total cholesterol (p=0.965); and HDL (p=0.885), and the level of LDL was significantly reduced (p=0.048).
Sengsuk C, 2015, Thailand [13]	Cinnamon group - 49; Placebo group - 50.	C. cassia bark powder 500 mg capsule TDS. Placebo - not specified 500 mg capsule TDS.	60 days	There was a significant reduction in the level of FBG, HbA1c, and triglyceride, and an increase of HDL (p<0.001). No desirable change had been found in LDL and total cholesterol (p>.001).