Insulin Also indexed as: Animal-Source Insulin: Iletin, Human Analog Insulin: Humanlog, Human Insulin (Humulin, Novolin), NovoRapid, Oralin
Insulin is a natural protein made by the pancreas that helps the body use sugar. Insulin is injected by all people with type 1 (insulin-dependent) diabetes mellitus and by some people with type 2 (non-insulin-dependent) diabetes mellitus to help control blood sugar levels.
Any substance (dietary, supplemental, herbal, and others) that affects blood sugar levels will directly or indirectly affect the amount of insulin required by a person with diabetes. For example, consumption of a high-fiber diet and/or supplementation with nutrients such as chromium, biotin, vitamin E, or herbs such as Gymnema sylvestre will often improve blood sugar control in diabetics. In such cases, the amount of insulin may need to be reduced in order to avoid a hypoglycemic reaction. Anyone taking insulin should consult the prescribing physician before making dietary changes or taking nutrients or herbs that are designed to lower blood sugar levels.
Summary of Interactions with Vitamins, Herbs, and Foods
In some cases, an herb or supplement may appear in more than one category, which may seem contradictory. For clarification, read the full article for details about the summarized interactions.
 May Be Beneficial: Depletion or interference—The medication may deplete or interfere with the absorption or function of the nutrient. Taking these nutrients may help replenish them. | DHEA |
| May Be Beneficial: Supportive interaction—Taking these supplements may support or otherwise help your medication work better. | Biotin Fenugreek Vitamin E |
 Avoid: Adverse interaction—Avoid these supplements when taking this medication because taking them together may cause undesirable or dangerous results. | Tobacco |
 Check: Other—Before taking any of these supplements or eating any of these foods with your medication, read this article in full for details. | Chromium Gymnema sylvestre* |
| Side effect reduction/prevention | None known |
| Reduced drug absorption/bioavailability | None known |
An asterisk (*) next to an item in the summary indicates that the interaction is supported only by weak, fragmentary, and/or contradictory scientific evidence.
Interactions with Dietary Supplements
Chromium
Chromium supplements have been shown to improve blood sugar control in people with diabetes.1 Consequently, supplementing with chromium could reduce blood sugar levels in people with taking insulin, potentially resulting in abnormally low blood sugar levels (hypoglycemia). While chromium supplementation may be beneficial for people with diabetes, its use in combination with insulin or with any other blood sugar-lowering medication should be supervised by a doctor.
Dehydroepiandrosterone (DHEA)
Insulin has been shown to decrease the levels of DHEA and DHEA-sulfate in the blood.2 More research is needed to determine the significance of this finding.
Interactions with Herbs
Fenugreek (Trigonella foenum-graecum)
In a controlled study of patients with type 1 diabetes, fenugreek (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.3 In a controlled study of people with type 2 diabetes, fenugreek (25 grams per day for 24 weeks) was reported to significantly reduce blood glucose levels.4 People using insulin should talk with their prescribing doctor before incorporating large amounts of fenugreek into their diet.
Gymnema sylvestre
Although no interactions have been reported, gymnema may decrease the required daily dose of insulin.5 Therefore, people currently using insulin for the treatment of diabetes should discuss the use of this herb with their healthcare professional.
Interactions with Foods and Other Compound
Food
Diet is an important factor in effective diabetes prevention and treatment. People using insulin should monitor their blood sugar carefully and talk with their doctor about the role of diet in diabetes control.
Alcohol
Alcohol may increase the action of insulin, leading to hypoglycemia (low blood sugar).6 People using insulin should avoid alcohol.
Tobacco (Nicotiana species)
Smoking may decrease insulin activity,7 and it compounds the health problems associated with diabetes. People using insulin are cautioned to avoid smoking.
References (To view, roll mouse over the "References" heading; to hide, click on the heading)
1. Anderson RA, Cheng N, Bryden NA, Polansky MM, Cheng N, Chi J, et al. Elevated intakes of supplemental chromium improve glucose and insulin variables in individuals with type 2 diabetes. Diabetes 1997;46:1786–91.
2. Lavallee B, Provost PR, Kahwash Z, et al. Effect of insulin on serum levels of dehydroepiandrosterone metabolites in men. Clin Endocrinol 1997;46:93–100.
3. Sharma RD, Raghuram TC, Sudhakar Rao N. Effect of fenugreek seeds on blood glucose and serum lipids in type 1 diabetes. Eur J Clin Nutr 1990;44:301–6.
4. Sharma RD, Sakar A, Hazra DK, et al. Use of fenugreek seed powder in the management of non-insulin dependent diabetes mellitus. Nutr Res 1996;16:1131–9.
5. Shanmugasundaram ER, Rajeswari G, Baskaran K, et al. Use of Gymnema sylvestre leaf extract in the control of blood glucose in insulin-dependent diabetes mellitus. J Ethnopharmacol 1990;30:281–94.
6. Threlkeld DS, ed. Hormones, Antidiabetic Agents, Insulin. In Facts and Comparisons Drug Information. St. Louis, MO: Facts and Comparisons, Oct 1997, 129f–9j.
7. Threlkeld DS, ed. Hormones, Antidiabetic Agents, Insulin. In Facts and Comparisons Drug Information. St. Louis, MO: Facts and Comparisons, Oct 1997, 129f–9j.
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The information presented in Healthnotes is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires September 2008.