Part1 Teas & high-carb foods

There are many teas which contain α-glucosidase inhibitor and thus are said to restrain postprandial hyperglycemia. So I tried some well-known teas to see if they really work. In each case, I drank some cups of tea 5-10 minutes BEFORE eating high-carb food, 250g of white rice which contain about 90g of carb (starch).

The blood glucose level after eating white rice only (w/o tea) is as follows:

  • Fasting: 80
  • 30min: 145
  • 60min: 214 (+134)
  • 120min: 167

Avocado Seed

Sliced avocado brewed in hot water.

Blood Glucose Level (mg/dl)

  • Fasting: 76
  • 30min: 169 (+91)
  • 60min: 151
  • 120min: 143

Banaba (Giant crape-myrtle / Lagerstroemia speciosa)

Corosolic acid contained in Banaba leaf works, like insulin, to facilitate the absorption of blood sugar into the cells.

Blood Glucose Level (mg/dl)

  • Fasting: 80
  • 30min: 155
  • 60min: 171 (+91)
  • 120min: 128

Black Bean Tea

Tea made from roasted black soy beans. Quite common in Japan but not sure if it’s “popular.”

Blood Glucose Level (mg/dl)

  • Fasting: 80
  • 30min: 165 (+85)
  • 60min:  152
  • 120min: 146

Burdock (Arctium lappa)

The root of the Burdock is very popular food in Japan. It contains plenty of inulin, a kind of dietary fiber, which may prevent the hyperglycemia.

Burdock root is also used to brew tea. Tastes a bit like earthy.



Blood Glucose Level (mg/dl)

  • Fasting: 70
  • 30min: 92
  • 60min: 130 (+60)
  • 120min: 113

Gymnema sylvestre

Gymnema sylvestre contains gymnema acid and gymnemoside, both of which are α-glucosidase inhibitors. It is said that, in south asia, Gymnema sylvestre has been used to treat DM patients for 2,000 years.

Blood Glucose Level (mg/dl)

  • Fasting: 80
  • 30min: 153
  • 60min: 166 (+86)
  • 120min: 148

Guava (Psidium guajava)

A polyphenol in Guava leaf inhibits α-maltase which decomposes the starch into glucose.

Blood Glucose Level (mg/dl)

  • Fasting: 78
  • 30min: 127
  • 60min: 172 (+94)
  • 120min: 159


Mulberry leaf contains α-glucosidase inhibitor called 1-deoxynojirimycin(DNJ).

This one is not processed leaf for brew but very finely powdered leaf just to mix with water.

Blood Glucose Level (mg/dl)

  • Fasting: 79
  • 30min:  117
  • 60min: 153
  • 120min: 158 (+79)

Rooibos (Redbush tea / Aspalathus linearis)

Rooibos leaf contains pinitol, a substance which is expected to control the blood glucose level. 

Blood Glucose Level (mg/dl)

  • Fasting: 80
  • 30min: 142 (+62)
  • 60min: 126
  • 120min: 130

Salacia oblonga

Salacia is used for the treatment of DM in traditional medicine. Salacia root contains α-glucosidase inhibitor salacinol.

This product is a powdered salacia extract soluble to water.

Blood Glucose Level (mg/dl)

  • Fasting: 80
  • 30min: 108
  • 60min: 133 (+53)
  • 120min: 129

Tea with Indigestible Dextrin

This product is one of the “Food for Specified Health Uses (FOSHU).” It contains indigestible dextrin which may restrain the absorption of fat and carbohydrate into the body.

Blood Glucose Level (mg/dl)

  • Fasting: 67
  • 30min: 123
  • 60min: 165 (+98)
  • 120min: 162

Summary of Part 1

This is the graph of how much my BGL rose after drinking each tea and eating 250g of white rice. It also shows how much each tea restrained the rise of BGL.

As you can see, all teas were effective in lowering the BGL more or less, much better than no tea at all.

However, the effectiveness varies. Salacia, Burdock and Rooibos work very well in my body.

Let me know if you know something as good as or better than these stuff.

Part 2: Other drinks and liquid foods


(coming soon)


Beer & Non-sugar Beer

Corn Potage (hot & cold)

Milk & Lactose-free Milk



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