In a randomized study of 15 patients with type 1 (insulin-dependent) diabetes, fenugreek (Trigonella foenum-graecum) (100 grams per day for ten days) was reported to reduce blood sugar, urinary sugar excretion, serum cholesterol, and triglycerides, with no change in insulin levels, compared with ten days of placebo. In a study of 60 people with type 2 diabetes, fenugreek (25 grams per day for 24 weeks) was reported to significantly reduce blood glucose levels. People using glipizide should talk with their doctor before making any therapy changes.

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In a preliminary trial, administration of Ginkgo biloba who were taking oral anti-diabetes medication resulted in a significant worsening of glucose tolerance. Ginkgo did not impair glucose tolerance in individuals whose diabetes was controlled by diet. Individuals taking oral anti-diabetes medication should consult a doctor before taking Ginkgo biloba.

Herbs such as Gymnema sylvestre will often improve blood-sugar control in diabetics.