Cinnamon Supplementation in Patients with Type 2 Diabetes Mellitus

Antony Q. Pham, B.S.; Helen Kourlas, Pharm.D.; David Q. Pham, Pharm.D.

Disclosures

Pharmacotherapy. 2007;27(4):595-599. 

In This Article

Abstract and Introduction

Abstract

Diabetes mellitus is the sixth leading cause of death in the United States, and most patients with the disease have type 2 diabetes. The effectiveness of cinnamon supplementation in patients with type 2 diabetes has received a great deal of media attention after a study was published in 2003. Although the efficacy of cinnamon in patients with diabetes has not been established, many patients seek other therapies and supplement their prescribed pharmacologic therapy with cinnamon. We conducted a literature search, limited to English-language human studies, using MEDLINE (1966-August 2006), EMBASE (1980-August 2006), International Pharmaceutical Abstracts (1970-August 2006), and Iowa Drug Information Service (1966-August 2006). References from articles and clinical trials were reviewed for additional sources; no abstracts were reviewed. We found two prospective, randomized, double-blind, placebo-controlled, peer-reviewed clinical trials and one prospective, placebo-controlled, peer-reviewed clinical trial that evaluated the efficacy of cinnamon supplementation in patients with type 2 diabetes; a total of 164 patients were involved in these trials. Two of the studies reported modest improvements in lowering blood glucose levels with cinnamon supplementation in small patient samples. One trial showed no significant difference between cinnamon and placebo in lowering blood glucose levels. Overall, cinnamon was well tolerated. These data suggest that cinnamon has a possible modest effect in lowering plasma glucose levels in patients with poorly controlled type 2 diabetes. However, clinicians are strongly urged to refrain from recommending cinnamon supplementation in place of the proven standard of care, which includes lifestyle modifications, oral antidiabetic agents, and insulin therapy.

Introduction

Type 2 diabetes mellitus is a metabolic disorder characterized by hyperglycemia and abnormalities in fat, carbohydrate, and protein metabolism. This progressive disorder can lead to micro-vascular and macrovascular complications.[1,2] Diabetes is the sixth leading cause of death in the United States and a major health concern, with approximately 8% of the population affected.[1] Its worldwide prevalence in 2000 was an estimated 2.8%, and its projected prevalence for 2030 is 4.4%.[3] According to the American Diabetes Association (ADA), type 2 diabetes accounts for 90-95% of patients with diabetes.[1]

Nonpharmacologic management of type 2 diabetes involves lifestyle modifications, with the promotion of a reduced-calorie diet and aerobic exercise. The ADA recommends that pharmacologic interventions be directed at achieving a glycosylated hemoglobin (A1C) less than 7%, preprandial plasma glucose level 90-130 mg/dl, and postprandial plasma glucose level below 180 mg/dl.[1] Due to these specific guideline recommendations, patients may become discouraged when they cannot achieve the goals and may seek alternative therapies.

The effectiveness of cinnamon supplemen-tation in patients with type 2 diabetes received a great deal of media attention after the publication of a study in 2003.[4] Consequently, many patients began supplementing their prescribed pharmacologic therapy with cinnamon.[5] Although the complete mechanism of action of cinnamon is still being investigated, several in vitro studies have found that it displays insulin-like effects.[5,6,7,8]

Cinnamon contains a biologically active substance initially classified as methylhydroxy-chalcone polymer (MHCP).[9,10] The MHCP stimulates the insulin receptor kinase, leading to autophosphorylation of the insulin receptor substrate 1. This action results in increased glucose uptake in adipocytes. Glycogen synthesis also increases with MHCP activity. Combining MHCP and insulin provided synergistic effects on both glucose uptake and glycogen production in vitro.

However, other findings suggested that the previously identified MHCP in cinnamon may have actually been water-soluble polyphenolic type-A polymers.[6,9] Thus, the biologically active insulin-like substance in cinnamon remains unidentified. In vivo, oral administration of cinnamon extract has enhanced glucose utilization in rats by increasing the glucose infusion rate into skeletal muscle.[11]

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