Several herbs may help in managing symptoms associated with diabetes, including the control of blood sugar levels.
AloeAnimal research and preliminary controlled human trials have found that Aloe vera, either alone or in combination with the oral hypoglycemic drug glibenclamide, effectively lowers blood sugar in people with type 2 diabetes.211 212 213 214 The typical amount used in this research was 1 tablespoon (15 ml) of aloe gel per day.
CayenneDouble-blind trials have shown that topical application of creams containing 0.025 to 0.075% capsaicin (from cayenne [Capsicum frutescens]) can relieve symptoms of diabetic neuropathy (numbness and tingling in the extremities caused by diabetes).215 216 Four or more applications per day may be required to relieve severe pain. This should be done only under a doctor�s supervision.
FenugreekFenugreek seeds are high in soluble fiber, which helps lower blood sugar by slowing down carbohydrate digestion and absorption.217 Animal research suggests that fenugreek may also contain a substance that stimulates insulin production and improves blood sugar control.218 219 In a controlled trial, incorporating 15 grams of powdered fenugreek seed into a meal eaten by people with type 2 diabetes reduced the rise in blood glucose following the meal.220 Another controlled trial found that taking 2.5 grams of fenugreek twice a day for three months reduced blood sugar levels in people with mild, but not those with severe, type 2 diabetes.221 In a double-blind study, 1 gram per day of an extract of fenugreek seeds for two months improved some measures of blood sugar control and insulin function in people with type 2 diabetes.222
PsylliumSupplementing with psyllium has been shown to be a safe and well-tolerated way to improve control of blood glucose and cholesterol. In a double-blind trial, men with type 2 diabetes who took 5.1 grams of psyllium per day for eight weeks lowered their blood glucose levels by 11 to 19.2%, their total cholesterol by 8.9%, and their LDL (bad) cholesterol by 13%, compared with a placebo.223
Asian ginsengAsian ginseng is commonly used in Traditional Chinese Medicine to treat diabetes. It has been shown in test tube and animal studies to enhance the release of insulin from the pancreas and to increase the number of insulin receptors.224 225 Animal research has also revealed a direct blood sugar�lowering effect of ginseng.226 A double-blind trial found that 200 mg of ginseng extract per day improved blood sugar control, as well as energy levels in people with type 2 diabetes.227
American ginsengIn a small preliminary trial, 3 grams of American ginseng was found to lower the rise in blood sugar following the consumption of a high-glucose drink by people with type 2 diabetes.228 The study found no difference in blood sugar�lowering effect if the herb was taken either 40 minutes before the drink or at the same time. A follow-up to this study found that increasing the amount of American ginseng to either 6 or 9 grams did not increase the effect on blood sugar following the high-glucose drink in people with type 2 diabetes.229 This study also found that American ginseng was equally effective in controlling the rise in blood sugar whether it was given together with the drink or up to two hours before.
BasilPreliminary trials of holy basil (Ocimim sanctum) leaves and hairy basil (Ocimum canum) seeds have shown that these herbs may help people with type 2 diabetes control their blood sugar levels.230 231 232 While the mechanism of action of holy basil leaf is not understood, hairy basil seed may work by replacing simple sugars in the diet, which rapidly and detrimentally elevate blood sugar levels, with dietary fiber, which raises blood sugar levels more slowly for better control. It is unknown whether common culinary sweet basil (Ocimum basilicum) would have similar effects.
GymnemaGymnema may stimulate the pancreas to produce insulin in people with type 2 diabetes. Gymnema also improves the ability of insulin to lower blood sugar in people with both type 1 and type 2 diabetes. So far, no double-blind trials have confirmed the efficacy of gymnema for people with any type of diabetes. However, a preliminary study of type 2 diabetics reported that 400 mg per day of gymnema extract taken for periods of 18 months or longer resulted in improvement, according to diabetes blood tests, and allowed reduction of diabetic medications.233 In a controlled trial with type 1 (insulin-dependent) diabetics, a similar amount of gymnema extract reduced requirements for insulin.234 Whether the extract used in these studies was standardized for active constituents is unclear. Recently, a preliminary trial found improved blood sugar levels after three months in a group of type 1 and type 2 diabetics who took 800 mg per day of an extract standardized for 25% gymnemic acids.235 Gymnema is not a substitute for insulin, but insulin amounts may need to be lowered while taking gymnema to avoid hypoglycemia.
Bitter melonWhole, fried slices,236 water extracts,237 and juice of bitter melon may improve blood-sugar control in people with type 2 diabetes,238 according to preliminary trials. However, double-blind trials are needed to confirm this potential benefit.
CinnamonTest tube studies have suggested that cinnamon may improve the glucose utilization. In a study of people with type 2 diabetes, supplementing with cinnamon in the amount of 1, 3, or 6 grams per day for 40 days was significantly more effective than a placebo at reducing blood glucose levels.239 The reduction averaged 18 to 29% in the three treatments groups, and 1 gram per day was as effective as 3 and 6 grams per day. However, in a double-blind study, supplementation with 1.5 g of cinnamon per day for six weeks was no more effective than a placebo for reducing blood sugar levels.240
Crepe myrtleLagerstroemia speciosa, commonly known as crepe myrtle, grows in various tropical countries and Australia. In folk medicine it has been used to treat diabetes. In a preliminary study of people with type 2 diabetes, supplementing with an extract from the leaves of Lagerstroemia speciosa for two weeks resulted in a fall in blood-glucose levels averaging 20 to 30%.241 The amount used was 32 or 48 mg of a product standardized to contain 1% corosolic acid (a putative active ingredient). The larger amount was somewhat more effect than the smaller amount. Although these results are promising, additional studies are needed to demonstrate the long-term safety and efficacy of this herbal preparation.
OnionPreliminary trials and at least one double-blind trial have shown that large amounts of onion can lower blood sugar levels in people with diabetes.242 243 244 The mechanism of onion�s blood sugar-lowering action is not precisely known, though there is evidence that constituents in onions block the breakdown of insulin in the liver. This would lead to higher levels of insulin in the body.245
BilberryBilberry may lower the risk of some diabetic complications, such as diabetic cataracts and retinopathy. One preliminary trial found that supplementation with a standardized extract of bilberry improved signs of retinal damage in some people with diabetic retinopathy.246
A�a�A�a� is reported to be a traditional remedy for diabetes. Although oxidative stress may contribute to diabetes247 and anthocyanins may improve insulin secretion,248 there is no published evidence that a�a� has any effect on diabetes.
GinkgoGinkgo biloba extract may prove useful for prevention and treatment of early-stage diabetic neuropathy, though research is at best very preliminary in this area.249
HibiscusHibiscus is a traditional remedy in India for diabetes; this treatment is supported by preliminary studies from that country and by animal studies.250 251 Hibiscus is usually taken as tea, such as 1 to 2 teaspoons (3 to 6 grams) of dried flower infused in to 1 cup (250 ml) three times per day.
MistletoeMistletoe extract has been shown to stimulate insulin release from pancreas cells,252 and animal research found that it reduces symptoms of diabetes.253 No research in humans has yet been published; however, given mistletoe�s worldwide reputation as a traditional remedy for diabetes, clinical trials are warranted to validate these promising preliminary findings. Traditionally, mistletoe is prepared by soaking 2 to 4 teaspoons (5 to 12 grams) of chopped mistletoe in 2 cups (500 ml) of water overnight. The mixture is drunk first thing in the morning and sweetened with honey if desired. Another batch may be left to steep during the day and drunk at bedtime.
Olive leafOlive leaf extracts have been used experimentally to lower elevated blood-sugar levels in diabetic animals.254 These results have not been reproduced in human clinical trials.
ReishiAnimal studies and some very preliminary trials in humans suggest reishi may have some beneficial action in people with diabetes.255 256
Are there any side effects or interactions?Refer to the individual herb for information about any side effects or interactions.
AloeAnimal research and preliminary controlled human trials have found that Aloe vera, either alone or in combination with the oral hypoglycemic drug glibenclamide, effectively lowers blood sugar in people with type 2 diabetes.211 212 213 214 The typical amount used in this research was 1 tablespoon (15 ml) of aloe gel per day.
CayenneDouble-blind trials have shown that topical application of creams containing 0.025 to 0.075% capsaicin (from cayenne [Capsicum frutescens]) can relieve symptoms of diabetic neuropathy (numbness and tingling in the extremities caused by diabetes).215 216 Four or more applications per day may be required to relieve severe pain. This should be done only under a doctor�s supervision.
FenugreekFenugreek seeds are high in soluble fiber, which helps lower blood sugar by slowing down carbohydrate digestion and absorption.217 Animal research suggests that fenugreek may also contain a substance that stimulates insulin production and improves blood sugar control.218 219 In a controlled trial, incorporating 15 grams of powdered fenugreek seed into a meal eaten by people with type 2 diabetes reduced the rise in blood glucose following the meal.220 Another controlled trial found that taking 2.5 grams of fenugreek twice a day for three months reduced blood sugar levels in people with mild, but not those with severe, type 2 diabetes.221 In a double-blind study, 1 gram per day of an extract of fenugreek seeds for two months improved some measures of blood sugar control and insulin function in people with type 2 diabetes.222
PsylliumSupplementing with psyllium has been shown to be a safe and well-tolerated way to improve control of blood glucose and cholesterol. In a double-blind trial, men with type 2 diabetes who took 5.1 grams of psyllium per day for eight weeks lowered their blood glucose levels by 11 to 19.2%, their total cholesterol by 8.9%, and their LDL (bad) cholesterol by 13%, compared with a placebo.223
Asian ginsengAsian ginseng is commonly used in Traditional Chinese Medicine to treat diabetes. It has been shown in test tube and animal studies to enhance the release of insulin from the pancreas and to increase the number of insulin receptors.224 225 Animal research has also revealed a direct blood sugar�lowering effect of ginseng.226 A double-blind trial found that 200 mg of ginseng extract per day improved blood sugar control, as well as energy levels in people with type 2 diabetes.227
American ginsengIn a small preliminary trial, 3 grams of American ginseng was found to lower the rise in blood sugar following the consumption of a high-glucose drink by people with type 2 diabetes.228 The study found no difference in blood sugar�lowering effect if the herb was taken either 40 minutes before the drink or at the same time. A follow-up to this study found that increasing the amount of American ginseng to either 6 or 9 grams did not increase the effect on blood sugar following the high-glucose drink in people with type 2 diabetes.229 This study also found that American ginseng was equally effective in controlling the rise in blood sugar whether it was given together with the drink or up to two hours before.
BasilPreliminary trials of holy basil (Ocimim sanctum) leaves and hairy basil (Ocimum canum) seeds have shown that these herbs may help people with type 2 diabetes control their blood sugar levels.230 231 232 While the mechanism of action of holy basil leaf is not understood, hairy basil seed may work by replacing simple sugars in the diet, which rapidly and detrimentally elevate blood sugar levels, with dietary fiber, which raises blood sugar levels more slowly for better control. It is unknown whether common culinary sweet basil (Ocimum basilicum) would have similar effects.
GymnemaGymnema may stimulate the pancreas to produce insulin in people with type 2 diabetes. Gymnema also improves the ability of insulin to lower blood sugar in people with both type 1 and type 2 diabetes. So far, no double-blind trials have confirmed the efficacy of gymnema for people with any type of diabetes. However, a preliminary study of type 2 diabetics reported that 400 mg per day of gymnema extract taken for periods of 18 months or longer resulted in improvement, according to diabetes blood tests, and allowed reduction of diabetic medications.233 In a controlled trial with type 1 (insulin-dependent) diabetics, a similar amount of gymnema extract reduced requirements for insulin.234 Whether the extract used in these studies was standardized for active constituents is unclear. Recently, a preliminary trial found improved blood sugar levels after three months in a group of type 1 and type 2 diabetics who took 800 mg per day of an extract standardized for 25% gymnemic acids.235 Gymnema is not a substitute for insulin, but insulin amounts may need to be lowered while taking gymnema to avoid hypoglycemia.
Bitter melonWhole, fried slices,236 water extracts,237 and juice of bitter melon may improve blood-sugar control in people with type 2 diabetes,238 according to preliminary trials. However, double-blind trials are needed to confirm this potential benefit.
CinnamonTest tube studies have suggested that cinnamon may improve the glucose utilization. In a study of people with type 2 diabetes, supplementing with cinnamon in the amount of 1, 3, or 6 grams per day for 40 days was significantly more effective than a placebo at reducing blood glucose levels.239 The reduction averaged 18 to 29% in the three treatments groups, and 1 gram per day was as effective as 3 and 6 grams per day. However, in a double-blind study, supplementation with 1.5 g of cinnamon per day for six weeks was no more effective than a placebo for reducing blood sugar levels.240
Crepe myrtleLagerstroemia speciosa, commonly known as crepe myrtle, grows in various tropical countries and Australia. In folk medicine it has been used to treat diabetes. In a preliminary study of people with type 2 diabetes, supplementing with an extract from the leaves of Lagerstroemia speciosa for two weeks resulted in a fall in blood-glucose levels averaging 20 to 30%.241 The amount used was 32 or 48 mg of a product standardized to contain 1% corosolic acid (a putative active ingredient). The larger amount was somewhat more effect than the smaller amount. Although these results are promising, additional studies are needed to demonstrate the long-term safety and efficacy of this herbal preparation.
OnionPreliminary trials and at least one double-blind trial have shown that large amounts of onion can lower blood sugar levels in people with diabetes.242 243 244 The mechanism of onion�s blood sugar-lowering action is not precisely known, though there is evidence that constituents in onions block the breakdown of insulin in the liver. This would lead to higher levels of insulin in the body.245
BilberryBilberry may lower the risk of some diabetic complications, such as diabetic cataracts and retinopathy. One preliminary trial found that supplementation with a standardized extract of bilberry improved signs of retinal damage in some people with diabetic retinopathy.246
A�a�A�a� is reported to be a traditional remedy for diabetes. Although oxidative stress may contribute to diabetes247 and anthocyanins may improve insulin secretion,248 there is no published evidence that a�a� has any effect on diabetes.
GinkgoGinkgo biloba extract may prove useful for prevention and treatment of early-stage diabetic neuropathy, though research is at best very preliminary in this area.249
HibiscusHibiscus is a traditional remedy in India for diabetes; this treatment is supported by preliminary studies from that country and by animal studies.250 251 Hibiscus is usually taken as tea, such as 1 to 2 teaspoons (3 to 6 grams) of dried flower infused in to 1 cup (250 ml) three times per day.
MistletoeMistletoe extract has been shown to stimulate insulin release from pancreas cells,252 and animal research found that it reduces symptoms of diabetes.253 No research in humans has yet been published; however, given mistletoe�s worldwide reputation as a traditional remedy for diabetes, clinical trials are warranted to validate these promising preliminary findings. Traditionally, mistletoe is prepared by soaking 2 to 4 teaspoons (5 to 12 grams) of chopped mistletoe in 2 cups (500 ml) of water overnight. The mixture is drunk first thing in the morning and sweetened with honey if desired. Another batch may be left to steep during the day and drunk at bedtime.
Olive leafOlive leaf extracts have been used experimentally to lower elevated blood-sugar levels in diabetic animals.254 These results have not been reproduced in human clinical trials.
ReishiAnimal studies and some very preliminary trials in humans suggest reishi may have some beneficial action in people with diabetes.255 256
Are there any side effects or interactions?Refer to the individual herb for information about any side effects or interactions.
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