Written by Charles Gumbley, BHSc (Clinical Nutrition), DipHSc (Western Herbal Medicine), ANTA registered practitioner
Last evidence check: 19 July 2026
This content is for general educational purposes only and is not intended as personalised medical advice. If you have raised blood glucose, take glucose-lowering medicine, or are pregnant or breastfeeding, consult a qualified healthcare professional before starting or changing a supplement.
Key takeaways
- No universal best supplement for insulin resistance has been established.
- Insulin resistance, prediabetes, type 2 diabetes, PCOS and metabolic syndrome are related but different clinical questions.
- Symptoms and body shape cannot diagnose insulin resistance. Australian assessment uses recognised risk tools and blood tests.
- Berberine has trial signals, but it is pharmacologically active and has important interaction and pregnancy cautions.
- Current evidence does not support a routine magnesium, chromium, inositol or vitamin D stack for everyone.
Conflict disclosure: Nutrition Market sells supplements. This guide does not rank brands, and all commercial product feeds remain disabled during clinical review.
Insulin resistance supplements: what evidence supports
A universal ranked list cannot answer this clinical question. The relevant issue is whether an ingredient has reliable evidence in a population like yours, changes an outcome that matters, and is safe with your medicines and health conditions.
Insulin resistance occurs when tissues do not respond to insulin normally. The pancreas may compensate by increasing insulin production, but blood glucose levels can rise over time. Prediabetes and type 2 diabetes are defined using glucose-related tests, not by choosing a supplement from an online symptom checklist.¹ ²
As a clinical nutritionist, I first want to know what has actually been measured. A fasting insulin result, HOMA-IR value, HbA1c result and oral glucose tolerance test do not answer exactly the same question. The diagnosis, medicine list, dietary pattern and reason for testing should come before a product decision.
Search language also needs care. Claims that supplements can help, enhance insulin action, reduce insulin resistance or improve blood sugar may refer to a short trial and a surrogate marker. They do not prove that a product prevents type 2 diabetes, reverses prediabetes or replaces prescribed care.
This is not an “8 best supplements” or “8 supplements” list. Certain supplements have shown short-term effects on insulin or glucose markers, but phrases such as “supplements may improve”, “increase insulin sensitivity”, “help manage blood sugar” and “support healthy blood sugar levels” require population, preparation and outcome context. Dietary supplements may also alter medicine effects.
Insulin resistance and blood sugar are not a diagnosis
Insulin helps glucose move from the blood into cells for energy. When cells respond to insulin less effectively, the body may need more insulin to maintain normal glucose. This is known as insulin resistance, but the term is used differently across research and clinical practice.
At cell level, insulin binds to the insulin receptor and activates a signalling pathway that helps regulate glucose uptake. When tissues become less sensitive to insulin, blood glucose and insulin levels may remain higher. Insulin resistance over time can increase the risk of developing type 2 diabetes, but risk is not destiny and cannot be read from one symptom.
Insulin resistance and type 2 diabetes are not synonyms. Lower sensitivity to insulin can precede dysglycaemia, while some people maintain blood sugar within the reference range for years. Inactivity, sleep apnoea, some medicines and excess visceral fat can worsen insulin resistance, but causes and clinical priorities differ.
Healthdirect notes that prediabetes usually has no symptoms. RACGP guidance states there is no routine clinical role for measuring insulin or C-peptide to characterise insulin resistance in impaired fasting glucose, impaired glucose tolerance or type 2 diabetes. Fasting blood glucose, HbA1c and an oral glucose tolerance test are the recognised diagnostic tools used as appropriate.¹ ³
| Question | What can help answer it | What cannot confirm it |
|---|---|---|
| Am I at higher risk of type 2 diabetes? | AUSDRISK and a GP assessment | A supplement quiz or body-shape claim |
| Do I have prediabetes or diabetes? | Clinician-interpreted FBG, HbA1c or OGTT | Cravings, fatigue or skin changes alone |
| Do I have PCOS? | A structured medical assessment using accepted criteria | Insulin resistance alone |
| Is a supplement working? | A pre-agreed clinical outcome and safety monitoring | Feeling different after a few days |
See a GP if you have increased thirst, frequent urination, unexplained weight loss, blurred vision, recurrent infections or persistent fatigue. These symptoms have several causes, and some need prompt assessment.²
Supplements for insulin resistance: how to assess research
Evidence for supplements can vary by diagnosis, preparation, dose, background diet, baseline nutrient status and concurrent medicine. The use of supplements for improving insulin measures should be judged against the same standard as any other intervention.
Supplements may help correct a documented deficiency, but evidence about their effects on insulin resistance must be assessed separately. Fasting insulin levels can change without a clear improvement in longer-term health outcomes.
| Research population | Common outcome | Main interpretation limit |
|---|---|---|
| People with type 2 diabetes | HbA1c, fasting blood glucose or medicine-adjunct outcomes | Does not prove prevention in people without diabetes |
| People with prediabetes | Progression to diabetes, FBG, HbA1c or OGTT | Trial duration may be too short for long-term outcomes |
| Women with polycystic ovary syndrome | Ovulation, hormones, fasting insulin or HOMA-IR | PCOS-specific findings do not apply to everyone |
| People with metabolic syndrome | Waist, lipids, blood pressure and glucose | A mixed syndrome does not isolate insulin sensitivity |
| Healthy volunteers | Short-term glucose or insulin response | Does not establish treatment efficacy |
A systematic review and meta-analysis can still inherit weak trials, inconsistent products and selective reporting. A statistically significant reduction in fasting blood glucose may be small, and improvement in insulin sensitivity may not translate into fewer new cases or complications.
My professional approach is to separate correction of an identified deficiency from use of a pharmacologically active supplement. Those are different decisions, with different monitoring and risk.
Berberine and insulin sensitivity
Berberine is a plant alkaloid studied in type 2 diabetes and metabolic syndrome. A 2025 meta-analysis of placebo-controlled trials reported reductions in fasting glucose, triglycerides and waist circumference, but not every metabolic outcome improved. The authors still called for better-designed trials.⁸
That signal does not make berberine natural metformin. Studies vary in preparation, dose, background treatment and quality. Results in people with type 2 diabetes or metabolic syndrome do not establish that berberine is the best option for an Australian adult with an unconfirmed diagnosis.
Berberine commonly causes nausea, diarrhoea, constipation, bloating or abdominal discomfort. It can interact with medicines and may add to glucose-lowering effects. NCCIH advises that it should not be used during pregnancy or breastfeeding and should not be given to infants.⁶ Anyone taking metformin, insulin, a sulfonylurea or another glucose-lowering medicine should have a pharmacist or prescriber review before considering it.
Magnesium supplements and insulin resistance
Magnesium is involved in normal energy metabolism and insulin signalling, but mechanism is not the same as a treatment effect.
A July 2026 meta-analysis included 15 randomised trials with 1,085 participants who had diabetes or prediabetes. Magnesium supplementation did not significantly improve insulin levels or HOMA-IR overall, and dose or duration subgroups did not change that conclusion. Baseline insulin status may have modified response, which needs confirmation.⁷
Magnesium may still be appropriate when intake is inadequate or deficiency risk is present. That is a nutritional assessment, not evidence that routine magnesium supplements improve insulin resistance. Kidney impairment also changes magnesium safety, and some products add vitamin B6 or other ingredients that increase cumulative exposure.
Inositol, PCOS and women with polycystic ovary syndrome
Inositol is most often studied in PCOS. Insulin resistance in women with PCOS is common but not universal.
A systematic review prepared for the 2023 international PCOS guideline included 30 trials. It found possible benefits for some metabolic outcomes, but overall evidence for inositol in PCOS remained limited and inconclusive, with no clear basis for one universal formulation.⁹
Findings in women with PCOS cannot be generalised to men, postmenopausal women, people with prediabetes for other reasons, or people with type 2 diabetes. The popular 40:1 myo-inositol to D-chiro-inositol ratio is also not proof that every commercial formula has superior clinical effects.
Chromium and blood sugar control
Chromium is marketed to support insulin sensitivity and glucose metabolism, but the clinical evidence is inconsistent.
The NIH Office of Dietary Supplements reports that any improvements in people with diabetes are generally small and of unclear clinical importance. Trials in metabolic syndrome have not consistently improved HbA1c, insulin sensitivity or fasting glucose.¹⁰ A 2024 systematic review also concluded that better-quality research is needed to define benefit and risk.¹¹
Chromium may add to the effects of insulin, metformin or other glucose-lowering medicines, increasing hypoglycaemia risk. Chromium picolinate can also reduce levothyroxine absorption when taken at the same time.¹⁰ These interaction questions matter more than a marketing claim about blood sugar control.
Vitamin D, deficiency and blood glucose levels
Vitamin D should be discussed in relation to measured status, dose, safety and the population studied.
A 2024 meta-analysis in people with type 2 diabetes reported modest average changes in fasting glucose, HbA1c, fasting insulin and HOMA-IR, with effects varying by baseline vitamin D, dose, duration, body mass index and glycaemic status.¹² That does not establish high-dose vitamin D as a general treatment for insulin resistance.
Correcting confirmed vitamin D deficiency may be appropriate for bone and general health. Taking more than needed can cause harm, including high calcium. Testing and clinician advice are particularly important with kidney disease, granulomatous disease, high calcium or medicines that affect calcium balance.
Manage insulin resistance with established care first
The strongest first-line approach is not a supplement stack. Healthdirect recommends a balanced diet, more physical activity and weight loss where appropriate for prediabetes.¹ RACGP recommends structured lifestyle intervention for impaired fasting glucose or impaired glucose tolerance, including at least 150 minutes of moderate-intensity physical activity per week and a goal of about 7% weight reduction where clinically appropriate.⁴
An insulin resistance diet is not one branded plan. A credentialled dietitian can adapt food quality, meal pattern, fibre, energy intake and cultural preferences to the person’s diagnosis and goals. Sleep, smoking, alcohol, medicines, physical activity and conditions such as PCOS or sleep apnoea can also affect metabolic risk.
Do not stop metformin, insulin or another prescribed medicine to trial a supplement. If glucose targets are not being met, medicine decisions should be made with the prescriber. New thirst, frequent urination, vomiting, marked weakness, confusion or unexplained weight loss needs medical assessment rather than a retail product.
Supplements that may help: Australian safety questions
Supplements that may help one measured deficiency or one trial population may be irrelevant or unsafe in another. In Australia, check the AUST L, AUST L(A) or AUST R number, but remember that an AUST number does not prove the product treats insulin resistance.⁵
Choosing supplements to help with a measured deficiency is different from taking insulin resistance supplements for an unconfirmed diagnosis.
Before starting any dietary supplement, ask:
- What diagnosis or measured deficiency is this intended to address?
- Does the evidence population match my situation?
- Could it add to metformin, insulin or another glucose-lowering medicine?
- Is it appropriate with pregnancy, breastfeeding, kidney disease or liver disease?
- What outcome and timeframe will be reviewed?
- Will I stop if there is no meaningful benefit or if adverse effects occur?
Which supplement options are best for insulin resistance?
No supplement is best for everyone. Berberine has some metabolic trial signals but also interactions and contraindications. Magnesium, chromium, inositol and vitamin D are context-specific or have mixed evidence. Start with diagnosis, established care and any identified nutritional need.
What is the best thing to reverse insulin resistance?
Avoid a guaranteed reversal claim. Structured dietary change, physical activity, weight management where appropriate, sleep and prescribed care can improve metabolic health. The right plan depends on whether you have prediabetes, type 2 diabetes, PCOS or another condition.
What are the seven signs of insulin resistance?
There is no reliable seven-sign checklist that can confirm insulin resistance. Prediabetes often has no symptoms. A GP can assess risk and decide whether FBG, HbA1c or an OGTT is appropriate.
Is berberine or inositol better for insulin resistance?
They have been studied in different populations. Berberine evidence often involves type 2 diabetes or metabolic syndrome, while inositol evidence is largely PCOS-specific and uncertain. Neither is a universal substitute for diagnosis or prescribed care.
Can supplements replace metformin for insulin resistance?
No supplement should replace metformin or another prescribed medicine without the prescriber’s advice. Combining products can also change glucose levels or side-effect risk, so discuss any addition with a pharmacist or clinician.
How long does it take for supplements to improve insulin sensitivity?
Trial duration does not predict individual benefit. If a clinician agrees that a trial is reasonable, decide in advance which outcome will be measured, when it will be reviewed and what safety monitoring is needed. Do not rely only on how you feel.
References
- Healthdirect Australia. Pre-diabetes. Healthdirect
- Healthdirect Australia. Type 2 diabetes. Healthdirect
- Royal Australian College of General Practitioners. Defining and diagnosing type 2 diabetes. RACGP
- Royal Australian College of General Practitioners. Management of type 2 diabetes: summary of recommendations. RACGP
- Therapeutic Goods Administration. Understanding complementary medicines. TGA
- National Center for Complementary and Integrative Health. Diabetes and dietary supplements: what you need to know. NCCIH
- Amiri A, Seighali F, Gholami-Chahkand MS, Jannat B, Seighali N. Oral magnesium supplements and insulin resistance in individuals with diabetes and pre-diabetes: an updated systematic review and meta-analysis of randomized controlled trials. BMC Nutrition. 2026. doi:10.1186/s40795-026-01424-y. PubMed
- Liu D, Zhao H, Zhang Y, Hu J, Xu H. Efficacy and safety of berberine on the components of metabolic syndrome: a systematic review and meta-analysis of randomized placebo-controlled trials. Frontiers in Pharmacology. 2025;16:1572197. doi:10.3389/fphar.2025.1572197. PubMed
- Fitz V, et al. Inositol for Polycystic Ovary Syndrome: A Systematic Review and Meta-analysis to Inform the 2023 Update of the International Evidence-based PCOS Guidelines. Journal of Clinical Endocrinology & Metabolism. 2024;109(6):1630-1655. doi:10.1210/clinem/dgad762. PubMed
- National Institutes of Health Office of Dietary Supplements. Chromium: fact sheet for health professionals. NIH ODS
- Georgaki MN, et al. Chromium supplementation and type 2 diabetes mellitus: an extensive systematic review. Environmental Geochemistry and Health. 2024;46(12):515. doi:10.1007/s10653-024-02297-5. PubMed
- Chen W, Liu L, Hu F. Efficacy of vitamin D supplementation on glycaemic control in type 2 diabetes: an updated systematic review and meta-analysis of randomized controlled trials. Diabetes, Obesity and Metabolism. 2024. doi:10.1111/dom.15941. PubMed
- Journal of Clinical Endocrinology & Metabolism. Correction to the inositol review in reference 9. 2024;109(12):e2365. doi:10.1210/clinem/dgae588. Correction notice
Author bio
Charles Gumbley founded Nutrition Market to make evidence-informed supplement guidance more accessible. With a Bachelor of Health Science in Clinical Nutrition and a Diploma of Health Science in Western Herbal Medicine, he brings a practitioner’s perspective to product selection and review. Charles is registered with ANTA and practises from Sydney, with telehealth available nationally. Site content is educational and does not replace individualised clinical advice.
