There is an increase in use of complementary and alternative therapies as they are thought to be free of side effects due to their natural origin. However, herbal remedies are complex combinations of bioactive units, which may interact with prescription medications via pharmacokinetic or pharmacodynamic mechanisms and sometimes can lead to life-threatening situations. Especially in diabetes patients are often treated with multiple medications due to different comorbidities, and such patients use antidiabetic medications for their entire lives; thus, it is significant to spread the public awareness of herb interactions with antidiabetic drugs.
Many people often take herbal remedies with oral hypoglycemic agents without sufficient caution. However, co-administered herbs may modify the pharmacokinetic profile of hypoglycemic agents or increase of decrease their pharmacological effects, and thus lead to side effects resulting from failure to regulate blood sugar levels. These risks are particularly serious due to the long-term nature of therapy for diabetic patients (Rehman, Choi, Choe, and Yoo, 2015).
Absorption of drugs can be impaired when herbs that contain hydrocolloidal fibers, gums, and mucilage are taken together. Such products include aloe gel, flaxseed, marshmallow, psyllium, and rhubarb. These herbals can bind to drugs and prevent absorption, and thus reduce systemic availability.
An herb might produce the same effect as a drug and thus enhance this effect when taken together. Additive blood-glucose-lowering effects are produced when agrimony extract is taken with oral hypoglycemics. The blood glucose-lowering effects of antidiabetics can be increased by vegetables like Bitter gourd (Momordica charantia) due to its hypoglycemic effects.
The most common interactions of herbs with antidiabetic drugs are those that result in a rise or fall in blood glucose levels, thereby upsetting the control of diabetes. Antidiabetic drugs that have been found to have a probability of interacting with herbal products include CYP2C8 substrates pioglitazone, repaglinide, and rosiglitazone; CYP2C9 substrates glibenclamide, glimepiride, glipizide, nateglinide, and rosiglitazone; CYP2C19 substrate proguanil; and CYP3A4 substrates pioglitazone and repaglinide (Rehman, Choi, Choe, and Yoo, 2015).
However, clinical and experimental data on herb–drug interactions, including antidiabetic-herb interactions, is inadequate, hence more research should be directed towards balanced use of herbal medicines both alone and in combination with conventional medicines.
Reference
Rehman, S. U., Choi, M. S., Choe, K., & Yoo, H. H. (2015). Interactions between herbs and antidiabetics: an overview of the mechanisms, evidence, importance, and management. Archives of pharmacal research, 38(7), 1281-1298.