Report on a Clinical Trial of Nettle Extract on Patients with Diabetes

The humble nettle may safely improve glycemic control in type 2 diabetic patients and also reduce inflammatory markers. Tests on nettle leaf, taken as capsules or as a tincture were carried out with promising results.

In 2013 the results of an interesting  randomised double-blind placebo-controlled clinical trial were published. Following is the abstract from this study by Kianbakht, S., Khalighi-Sigaroodi, F & Dabaghian which builds on previous studies that demonstrated the efficacy of nettle leaf tincture.

"Advanced type 2 diabetes mellitus (T2DM) needing insulin therapy is common. Most conventional anti-hyperglycemic drugs have limited efficacies and significant side effects, so that better anti-hyperglycemic agents are needed. Urtica dioica L. (nettle) leaves have insulin secretagogue, PPARgamma agonistic, and alpha-glucosidase inhibitory effects. Moreover, nettle leaves are used in traditional medicine as an anti-hyperglycemic agent to treat diabetes mellitus. Thus, efficacy and safety of nettle in the treatment of patients with advanced type 2 diabetes mellitus needing insulin were studied.

In this randomized double-blind placebo-controlled clinical trial, we evaluated the effects of taking nettle leaf extract (one 500 mg capsule every 8 hours for 3 months) combined with the conventional oral anti-hyperglycemic drugs on the blood levels of fasting glucose, postprandial glucose, glycosylated hemoglobin (HbA1c), creatinine and liver enzymes SGOT and SGPT, and systolic and diastolic blood pressures in 46 patients and compared with the placebo group (n = 46).

At the endpoint, the extract lowered the blood levels of fasting glucose, 2 hours postprandial glucose, and HbA1c significantly (p < 0.001, p = 0.009, and p = 0.006, respectively) without any significant effects on the other parameters (p > 0.05) compared with placebo.

Nettle may safely improve glycemic control in type 2 diabetic patients needing insulin therapy."

This work builds on the 2011 results in a study by Namazi, Esfanjani, Heshmati & Bahrami who studied the effects of a hydro alcoholic extract (tincture) of Nettle (Urtica dioica) on insulin sensitivity and some inflammatory indicators in type 2 diabetic patients. This was a randomized double-blind clinical trial on 50 men and women with type 2 diabetes done over an 8 week period. Patients were adjusted by age, sex and duration of diabetes, then randomly divided into two groups, an intervention and control group. They received, 100 mg kg-1 nettle extract or a placebo in three portions a day for 8 weeks.

Interleukin 6 (IL-6), Tumor Necrosis Factor-alpha (TNF-alpha), High Sensitive C-Reactive protein (hs-CRP) and Fasting Insulin concentration were measured. Insulin Sensitivity was calculated, at the beginning and the end of the study. The data were analyzed by SPSS version 18, p<0.05 was considered significant for all variables.

After 8 weeks, IL-6 and hs-CRP showed a significant decrease in the intervention group compared to the control group (p<0.05).

These findings showed that the nettle tincture has decreasing effects on IL-6 and hs-CRP in patients with type 2 diabetes after the eight week trial.

Kianbakht, S., Khalighi-Sigaroodi, F., & Dabaghian, F. (2013). Improved glycemic control in patients with advanced type 2 diabetes mellitus taking Urtica dioica leaf extract: a randomized double-blind placebo-controlled clinical trial.

Clin Lab. 59 (9-10), 1071-6.

Namazi, N., Esfanjani, A., Heshmati, J., & Bahrami, A. (2011). The effect of hydro alcoholic Nettle (Urtica dioica) extracts on insulin sensitivity and some inflammatory indicators in patients with type 2 diabetes: a randomized double-blind control trial. Pak J Biol Sci. 14(15), 775-9.