Supplementation in Type 2 Diabetes – Rationale, Benefits, and Safety

Supplements for Type 2 Diabetes

People with type 2 diabetes often look for therapeutic solutions that can improve their health, particularly those that help with blood glucose control.

Due to the growing prevalence of the disease, the market for diabetes-specific supplements is expanding. Most of these are plant-based products believed to potentially increase tissue insulin sensitivity and help stabilize blood glucose levels.

Safety of Supplements for People with Diabetes

The foundation of treating diabetes and other disorders of carbohydrate metabolism should always be a proper diet. Supplementation should only come after that.

If you decide to use supplements, pay attention to potential interactions with antidiabetic medications and possible side effects.

It is also important to know that dietary supplements are not subject to the same regulations as pharmaceutical drugs. Their composition and quality are not controlled to the same extent as registered medications.

What Vitamins and Supplements Are Commonly Used in Type 2 Diabetes?

You can find a variety of supplements for people with diabetes on the market. The most frequently used include:

• White mulberry

• Cinnamon

• Green tea

• Chromium

• Berberine

• Magnesium

• Bitter melon

• Chia seeds (Salvia hispanica)

• Alpha-lipoic acid

White Mulberry

White mulberry contains bioactive compounds with health-promoting properties. The leaves are a valuable source of nutrients, including:

• Protein and dietary fiber

• Micronutrients

• Ascorbic acid

• Beta-carotene

• Oxalates

• Phytates

• Tannic acid

• Polyphenols, such as flavonoids (e.g., quercetin, rutin, kaempferol) and phenolic acids

Thanks to compounds that inhibit the activity of enzymes involved in carbohydrate metabolism (α-glucosidase and maltase), white mulberry slows the breakdown of complex carbohydrates into simple sugars in the small intestine. This leads to slower glucose absorption and a smaller post-meal blood glucose spike.

A beneficial effect can be achieved by drinking an infusion made from 1 g of dried mulberry leaves steeped in 100 ml of water for about 5 minutes.

White mulberry also lowers LDL cholesterol due to its flavonoid and anthocyanin content, helping to reduce cardiovascular risk (1).

Cinnamon

Cinnamon is derived from the bark of an evergreen tree. For diabetes management, the relevant species is Cinnamomum cassia.

Studies show that adding this spice to the diet may help reduce blood glucose levels. However, dosing remains a challenge — studies use between 120 mg and 6 g per day in various forms (extract or ground cinnamon).

Cinnamomum cassia may reduce blood glucose levels by around 24 mg/dL and lower total cholesterol, triglycerides, and LDL cholesterol.

Daily doses of 1 g (half a teaspoon) have been associated with health benefits. In metabolic syndrome and polycystic ovary syndrome (PCOS), aqueous cinnamon extract is recommended due to its high polyphenol content (2).

Green Tea

Green tea contains a bioactive compound called epigallocatechin gallate (EGCG). Experimental studies show that EGCG may aid weight loss and improve glucose tolerance.

It also directly affects carbohydrate metabolism, helping to stabilize blood glucose. Up to 3 cups of green tea per day are recommended (3).

Chromium

Chromium is a trace element naturally found in:

• Whole grain products

• Green vegetables

• Legumes

• Meat

• Nuts

• Eggs

• Yeast

Due to the difficulty of measuring chromium levels in the blood, determining optimal concentrations in the body is challenging.

Trivalent chromium activates many enzymes involved in metabolic processes and is essential for proper insulin receptor function (4).

Some studies suggest chromium may improve insulin sensitivity and beta cell function. However, most of these studies are based on animal models and cannot be fully translated to humans.

Review papers indicate that noticeable effects on HbA1c and blood glucose occur mainly with yeast-based chromium supplements.

Some evidence supports chromium’s ability to lower fasting glucose but not HbA1c. Chromium picolinate is sometimes used as an adjunct in PCOS treatment.

There are also supplements combining chromium picolinate with biotin (a B vitamin involved in carbohydrate and lipid metabolism), which may enhance chromium’s glucose-lowering effect.

Although some benefits have been observed, current evidence is insufficient to recommend widespread chromium supplementation. Moreover, excessive chromium intake may be harmful, and its absorption can be reduced by simple sugars, zinc, and iron (4).

Magnesium

Magnesium is found in:

• Leafy green vegetables

• Legumes

• Nuts

• Whole grains

Low magnesium levels are linked to impaired glucose and insulin metabolism.

In people with type 2 diabetes and magnesium deficiency, supplementation improves insulin sensitivity and glycemic control markers (e.g., HbA1c, insulin, C-peptide, HOMA-IR) (5).

Bitter Melon

Bitter melon is used in Asian and Indian cuisine and is also known as:

• Balsam pear

• Bitter gourd

• Karela

• Ampalaya

• Balsamic pear

Studies suggest it can lower blood glucose and HbA1c levels.

It’s sometimes referred to as “plant insulin” due to its similar mechanism of action. It influences glucose absorption, reduces hepatic glucose production, and inhibits enzymes involved in glucose metabolism. When used alongside insulin-stimulating drugs, it may further lower blood glucose levels.

Available as juice, powder, suspensions, injections, or capsules, its effective and safe dosage remains unclear. Studies have used varied forms and doses, and the ideal duration of supplementation is unknown.

While consuming bitter melon as a food is considered safe, caution is advised when using supplements (6).

Chia Seeds (Salvia hispanica)

Chia seeds are a source of:

• Omega-3 fatty acids (especially alpha-linolenic acid)

• Fiber

• Protein

• Calcium

• Magnesium

• Iron

• Phytosterols and tocopherols (antioxidants)

Potential benefits include lower blood glucose and reduced insulin spikes after meals, likely due to chia’s high soluble fiber content, which forms a gel that slows glucose absorption.

Adding chia to meals may also promote satiety and support healthy digestion.

Chia appears to positively affect glycemia and blood pressure. However, in people with hypertriglyceridemia, it may raise triglyceride levels. Studies used doses ranging from 7–37 g, but no standardized effective dose has been established.

The current recommendation is a maximum of 15 g/day (2 tablespoons) (7). It should complement a healthy, varied diet — not replace it.

Alpha-lipoic acid

Natural sources of alpha-lipoic acid include meat and organ meats, as well as green vegetables. It has strong antioxidant and anti-inflammatory properties, which enhances the neutralization of free radicals. Additionally, this compound plays a role in the metabolism of macronutrients, mainly carbohydrates and fats.

Alpha-lipoic acid exhibits hypoglycemic effects, meaning it reduces blood glucose levels. This is associated with its ability to limit the accumulation of triacylglycerols in the pancreas, as excessive buildup of these compounds can damage the beta cells in the pancreatic islets.

It also helps prevent insulin resistance by enhancing insulin action in the following ways:

• stimulating glucose uptake by muscle cells,

• promoting glycogen synthesis,

• increasing glucose oxidation.

Alpha-lipoic acid is recommended by the Polish Diabetes Association as one of the pharmaceutical interventions in managing diabetic neuropathy. It is typically used in doses ranging from 300 to 600 mg per day, depending on the severity of symptoms.

Some studies show that supplementation with alpha-lipoic acid may lead to improved insulin sensitivity and better glucose control in people with type 2 diabetes. It is also thought to have a protective effect on nerve tissue, which is particularly important in diabetes-related complications.

Although alpha-lipoic acid appears to be generally well-tolerated, it may cause mild gastrointestinal side effects in some individuals. Always consult your doctor before starting supplementation, especially if you are taking other medications.

Summary

Numerous studies indicate that the right dietary approach is a key component in preventing and supporting the treatment of type 2 diabetes. Among the most effective dietary strategies is the Mediterranean diet, rich in fiber, healthy fats, and antioxidants. Its positive impact is due to its high content of fruits, vegetables, whole grains, legumes, and olive oil, which support the body’s sensitivity to insulin and help maintain normal blood glucose levels.

Equally important are nutrients and ingredients that can improve glucose metabolism and insulin sensitivity. Particular attention should be paid to compounds such as polyphenols (e.g. from cinnamon and green tea), resveratrol, alpha-lipoic acid, magnesium, zinc, chromium, and vitamin D. Each of these components plays a specific role in regulating carbohydrate metabolism and supporting pancreatic function.

However, before introducing any dietary supplements, it is worth checking their levels in the blood and consulting a doctor or dietitian. A properly composed diet, combined with physical activity and regular check-ups, remains the foundation of effective prevention and management of type 2 diabetes.