Aloe vera should be further investigated as a potential antidiabetic compound, say researchers after analyzing evidence that it lowered blood glucose in patients with diabetes and pre-diabetes.
The analysis is the work of researchers at the David Grant USAF Medical Center at Travis Air Force Base in Fairfield, CA, who report their findings in The Journal of Alternative and Complementary Medicine.
The analysis shows people with diabetes whose fasting blood glucose (FBG) is above 200 mg/dl may benefit the most from treatment with oral aloe vera.
Diabetes is a lifelong condition where blood sugar is too high, resulting in damage to organs if not treated. There are 382 million people worldwide living with diabetes, with type 2 diabetes accounting for the vast majority of cases.
The authors note that in the United States - where some 21 million people have the disease - the cost of treatment and loss of productivity in 2012 due to diabetes was $245 billion. The global cost is expected to "exceed a staggering $490 billion" by 2030.
People with diabetes are more likely to seek complementary and alternative medicines than people without diabetes. A popular remedy is aloe vera (Aloe barbadensis), a plant used medicinally by the Chinese, Egyptians, Greeks, Indians, Japanese, and Mexicans for thousands of years.
Aloe vera contains dozens of active compounds
The part of the aloe vera plant that is used medicinally is the leaves, the major components of which are the green outer rind and the colorless inner gel. Aloe vera products are made from either of these components, or both.
The aloe vera plant contains at least 75 active compounds, "which notably include vitamins, enzymes, minerals, anthraquinones, monosaccharide, polysaccharides, lignin, saponins, salicylic acids, phytosterols, and amino acids," note the authors, who also cite studies suggesting some of these compounds play a role in improving blood glucose control.
The plant also contains trace elements such as chromium, magnesium, manganese, and zinc, known to be important for glucose metabolism by improving the effectiveness of insulin.
Studies of oral aloe vera as a remedy for a range of chronic diseases - such as asthma, glaucoma, high blood pressure, inflammatory bowel disease, and diabetes - have produced limited or inconsistent evidence.
However, oral aloe vera is becoming more popular, and evidence about its effect on lowering blood glucose has been mounting, so the researchers decided to analyze it.
Evidence sufficient to warrant further investigation
For their analysis, the team looked for studies of the effect of oral aloe vera on fasting blood glucose (FBG), hemoglobin A1c (HbA1c), oral glucose tolerance test (OGTT), and a number of other measures in pre-diabetic and diabetic populations.
They found only nine studies had appropriate data for meta-analyses and covered FBG and HbA1c only. Of these, all nine measured FBG (total of 283 participants), and five measured HbA1c (89 participants).
FBG (sometimes called fasting plasma glucose, FPG) measures the blood glucose level during a period when the patient has not had anything to eat or drink, except water, for at least 8 hours. A level in the range of 100-125 mg/dl is defined as pre-diabetic and 126 mg/dl or higher as diabetic.
HbA1c (glycated hemoglobin, sometimes called haemoglobin A1c or simply A1c) is a measure of average blood glucose over the past 2-3 months. A level greater than or equal to 6.5 percent is considered diabetic.
The meta-analysis showed aloe vera decreased FBG by 46.6 mg/dl and HbA1c by 1.05 in the populations studied.
The researchers also note "the data suggest that patients with an FBG ≥200 mg/dl may see a greater benefit," and this population saw an average FBG reduction of 109.9 mg/dl.
In their conclusion, the researchers point to several limitations of the data and findings. For example, there were inconsistencies across studies in the formulation of aloe vera used, making it difficult to determine which products would be effective.
Other important shortcomings include: trial periods ranging from 4-14 weeks; differences in types of controls and comparisons with other medications and supplements; lack of blinding or randomization; and measuring how well participants followed their assigned regimens.
"Further clinical studies that are more robust and better controlled are warranted to further explore these findings."
William R. Dick et al.