ABSTRACT
<p><b>BACKGROUND</b>Propolis, a natural resinous substance made by bees from material extracted from plants, flowers and bee's wax, has shown great therapeutic effects and been widely used in food and drug industries. Recently, some researchers have studied the effect of this substance in the treatment of diabetes.</p><p><b>OBJECTIVE</b>The purpose of this trial was to determine the effect of bee propolis on glycemic control, serum lipid profile and insulin resistance indices in patients with type 2 diabetes (T2D).</p><p><b>DESIGN, SETTING, PARTICIPANTS AND INTERVENTIONS</b>This randomized clinical trial involved 66 patients with T2D, which were randomly divided into two groups of intervention (IG) and placebo (PG). IG received 300 mg three times a day for a total of 900 mg/d of propolis pills, while PG received similar pills, lacking propolis, on the same schedule for 12 weeks.</p><p><b>MAIN OUTCOME MEASURES</b>Fasting blood glucose (FBG), hemoglobin A1c (HbA1c), total cholesterol (TC), low-density lipoprotein (LDL), high-density lipoprotein (HDL), triglyceride (TG), serum insulin and insulin resistance indices were the main outcome measures.</p><p><b>RESULTS</b>The mean change in FBG between the IG ((17.76 ± 27.72) mg/dL decrease) and the PG ((6.48 ± 42.77) mg/dL increase) was significantly different (P = 0.01). Change in mean HbA1c had a similar pattern to FBG. The mean change in TC between the IG ((5.16 ± 43.80) mg/dL increase) and the PG ((28.9 ± 27.4) mg/dL increase) was also significantly different (P = 0.01), showing the protective role of propolis against the increase in TC. The change in mean LDL was similar to mean TC. There was no significant difference in other lipids or insulin resistance indices between the two groups.</p><p><b>CONCLUSION</b>Based on this study, the daily intake of 900 mg of bee propolis supplement for 12 weeks results in improvement of glycemic and some serum lipid levels in patients with T2D.</p><p><b>TRIAL REGISTRATION</b>This study is registered on the website of Iranian Ministry of Health (www.irct.ir) with proprietary code of IRCT2014080218659N1.</p>