VITAMIN D AND DIABETES

ON THIS PAGE
  • Vitamin D and Blood Sugar
  • Vitamin D Deficiency and Diabetes
  • The Potential Benefits of Vitamin D Supplementation
  • Recommended Vitamin D Intakes

Vitamin D plays a big role in how our bodies handle blood sugar, and low levels are linked to a higher chance of getting diabetes. While scientists are still figuring out if extra vitamin D can help manage the condition, it's worth understanding how this vital nutrient connects to diabetes and metabolic health and how to make sure you're getting enough.

Vitamin D and Blood Sugar

Vitamin D is critical for good health, and is well known to play a role in good bone health and a healthy immune system. The nutrient is also crucial to your body's ability to manage the hormone insulin and blood sugar levels. It does that in part by enhancing insulin's ability to transport glucose through the body, regulating calcium levels, and binding to beta-cell vitamin D receptors in the pancreas that are crucial for insulin secretion. It also stimulates the release of insulin into the bloodstream and helps lower inflammation, a key factor in insulin resistance and type 2 diabetes.

“It's easy to underestimate how critical this micronutrient is for big functions in the body, like improving insulin sensitivity,” explains Aimée José, RN, CDCES, a diabetes coach based in the San Diego area.

Clinical trials suggest that vitamin D directly affects blood glucose levels in several ways. It helps:
  • Stimulate and improve the pancreas' natural insulin secretion
  • Improve insulin sensitivity
  • Reduce inflammation throughout the body
  • Improve overall glucose levels
Low vitamin D levels can impair the function of cells that produce insulin, potentially impacting how the body is able to process blood sugar.

Vitamin D Deficiency and Diabetes

Vitamin D deficiency is very common, and can affect anyone, though it is most often found in people 65 or older and those who have darker skin. The condition is usually not serious, but severe deficiency can cause calcium and phosphorus imbalances, potentially leading to thyroid and bone issues, including an enhanced risk of fractures. Low levels may also lead to cardiovascular disease, autoimmune disorders, and depression.
It seems likely that vitamin D deficiency is also linked with the development of diabetes. Vitamin D deficiency appears to be especially prevalent in people with type 2 diabetes, and low vitamin D rates may increase the risk of type 1 diabetes.
“There is also a vitamin D hypothesis in type 1 diabetes,” says Benjamin Nwosu, MD, the chief of pediatric endocrinology at Northwell Health and a researcher at the Feinstein Institutes for Medical Research in Manhasset, New York. “It suggests that the further you move away from the equator, the higher the prevalence of autoimmune diseases like type 1 diabetes and rheumatoid arthritis. When you're getting enough vitamin D from the sun, it protects you from some of those autoimmune triggers.”
Vitamin D deficiency is also associated with a greater risk of gestational diabetes. and other metabolic health disorders that are often related to diabetes, including metabolic syndrome and cardiovascular disease.
Scientists don't fully understand how vitamin D deficiency might cause metabolic or autoimmune disorders. Healthy amounts of vitamin D lower inflammation in the liver, kidney, pancreas, and immune cells, which might help improve insulin sensitivity and the healthy functioning of fat cells. Lower vitamin D levels raise the risk of insulin resistance, the body's inability to properly use insulin, a root cause of type 2 diabetes and gestational diabetes.
Beyond the blood sugar disruptions it may cause, a lack of vitamin D may have a negative impact on muscle function, the immune system, and mood — all bodily systems related to diabetes. Low vitamin D levels can also worsen existing diabetes symptoms. For example, older people with diabetes are more likely to develop foot ulcers, and the severity of the ulcer grows if vitamin D levels worsened.

The Potential Benefits of Vitamin D Supplementation

Despite the wealth of evidence linking vitamin D intake to good metabolic health, there is relatively little proof that vitamin D supplementation will reduce the risk or ease the management of diabetes. Health authorities such as the American Diabetes Association do not endorse vitamin D supplementation as a therapy.
For those with type 1 diabetes, some research suggests that supplementation may help reduce A1C levels.
Dr. Nwsou says that vitamin D should be a critical part of type 1 diabetes management, especially in people who are newly diagnosed with the condition, as the nutrient could help preserve the life of insulin-producing cells in the pancreas.
Studies of type 2 supplementation in type 2 diabetes have mixed results, with some pointing to a modest positive effect on blood sugar results, and others finding no benefit at all.

Recommended Vitamin D Intakes

Despite the relative lack of evidence that vitamin D can prevent or improve diabetes symptoms, some experts recommend that people with diabetes should try to get enough of it anyway.
The primary reason to prioritize extra vitamin D is to reduce the risk of severe deficiency. Though this doesn't often occur in generally healthy people, vitamin D supplementation can significantly improve the health of people who have a real need for the nutrient. In everyone else, though the benefits may be questionable, there is likely no downside to supplementing with vitamin D.

Vitamin D is hard to come by in dietary sources, so supplements — and sunshine — are the best methods to do so. José says diabetes health authorities don't typically recommend that people with diabetes take any more vitamin D than what's suggested for the general population.

”The recommended daily allowance of vitamin D in the U.S. is about 600 IU for adults and 800 IU for senior citizens,” says José.

That said, some people with diabetes may need higher doses of vitamin D due to other health conditions or chronically low vitamin D levels.

If you'd like to soak up your vitamin D through sunshine, it's impossible to measure just how much you're getting. One study found that depending on the latitude, season, and clothing people wear, it can take only a few minutes to a couple of hours in the sun to produce a sufficient amount of vitamin D.
Nwosu says routine sun exposure is not enough to raise vitamin D levels to optimal levels, but it can help. And since sunscreen blocks ultraviolet light, it can reduce the amount of vitamin D that the skin can absorb.

“If you're not living in a tropical climate, or if you spend relatively little time outdoors, getting more vitamin D through a supplement may be advisable,” he says.

As for edible sources, vitamin D can be found in a limited variety of foods, including:
  • Fortified dairy and plant-based milks
  • Fortified breakfast cereals, orange juice, and yogurt
  • Fatty fish, such as trout, salmon, tuna, and mackerel
  • Fish liver oils
  • Beef liver
  • Egg yolks
  • Cheese
  • Mushrooms
Discuss vitamin D dosages with your diabetes care team. While rare, it is possible to use supplements to excess and suffer from vitamin D toxicity.

The Takeaway

  • Vitamin D plays a crucial role in glucose metabolism, including stimulating insulin secretion, improving insulin resistance, and reducing inflammation.
  • Vitamin D deficiency is associated with a higher risk of diabetes, and it can make existing diabetes symptoms worse.
  • Despite vitamin D's known connections to metabolic health, there is not much evidence that supplementing the vitamin will improve diabetes risk or disease progression.
  • Though vitamin D isn't considered an important therapy for diabetes, making an effort to meet minimum intake recommendations remains a valid approach to help maximize your health.

Resources We Trust

EDITORIAL SOURCES
Everyday Health follows strict sourcing guidelines to ensure the accuracy of its content, outlined in our editorial policy. We use only trustworthy sources, including peer-reviewed studies, board-certified medical experts, patients with lived experience, and information from top institutions.
Sources
Resources
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  2. Sung CC et al. Role of Vitamin D in Insulin Resistance. BioMed Research International.
  3. Sun LJ et al. Effects of Vitamin D Supplementation on Glucose and Lipid Metabolism in Patients With Type 2 Diabetes Mellitus and Risk Factors for Insulin Resistance. World Journal of Diabetes. October 15, 2023.
  4. Mirhosseini N. The Effect of Improved Serum 25-Hydroxyvitamin D Status on Glycemic Control in Diabetic Patients: A Meta-Analysis. Journal of Clinical Endocrinology and Metabolism. July 3, 2017.
  5. Low Vitamin D May Contribute to Insulin Resistance. American Diabetes Association.
  6. Vitamin D Deficiency. Cleveland Clinic. August 2, 2022.
  7. Kaur J et al. Vitamin D Deficiency. StatPearls. 2025.
  8. Prevalence of Vitamin D Deficiency in Type 2 Diabetes Mellitus Patients: A Cross-Sectional Study. National Library of Medicine. May 12, 2023.
  9. Vitamin D and Beta Cells in Type 1 Diabetes: A Systematic Review. National Library of Medicine. Nov 20, 2022.
  10. Dupuis ML et al. The Role of Vitamin D in Autoimmune Diseases: Could Sex Make the Difference? Biology of Sex Differences. January 12, 2021.
  11. Kokkinari A et al. The Association between Vitamin D Intake and Gestational Diabetes Mellitus: A Systematic Review. Clinical and Experimental Obstetrics & Gynecology. May 6, 2023.
  12. The Role of Vitamin D and Its Molecular Bases in Insulin Resistance, Diabetes, Metabolic Syndrome, and Cardiovascular Disease: State of the Art. National Library of Medicine. Oct 23, 2023.
  13. Ehampoush E et al. The Association of Vitamin D Levels and Insulin Resistance. Clinical Nutrition. April 2021.
  14. Diabetes and Dietary Supplements: What You Need to Know. National Center for Complementary and Integrative Health. November 2023.
  15. Abugoukh TM et al. Does Vitamin D Have a Role in Diabetes? Cureus. October 18, 2022.
  16. Effect of Ergocalciferol on β-Cell Function in New-Onset Type 1 Diabetes. JAMA Network Open. March 5, 2024.
  17. Vitamin D—A New Therapeutic Target in the Management of Type 2 Diabetes Patients. National Library of Medicine. Feb 28, 2024.
  18. Bouillon R et al. Health Effects of Vitamin D Supplementation: Lessons Learned From Randomized Controlled Trials and Mendelian Randomization Studies. Journal of Bone and Mineral Research. October 1, 2023.
  19. American Diabetes Association Professional Practice Committee. Comprehensive Medical Evaluation and Assessment of Comorbidities: Standards of Care in Diabetes — 2025. Diabetes Care. 2025.
  20. Ask the Doctors: How Much Sunshine Do I Need for Enough Vitamin D? UCLA Health.
  21. 6 Things You Should Know About Vitamin D. Harvard Health Publishing. October 13, 2020.
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  23. What Is Vitamin D Toxicity? Mayo Clinic. February 20, 2025.

Reyna Franco, RDN

Medical Reviewer

Reyna Franco, RDN, is a New York City–based dietitian-nutritionist, certified specialist in sports dietetics, and certified personal trainer. She is a diplomate of the American College of Lifestyle Medicine and has a master's degree in nutrition and exercise physiology from Columbia University.

In her private practice, she provides medical nutrition therapy for weight management, sports nutrition, diabetes, cardiac disease, renal disease, gastrointestinal disorders, cancer, food allergies, eating disorders, and childhood nutrition. To serve her diverse patients, she demonstrates cultural sensitivity and knowledge of customary food practices. She applies the tenets of lifestyle medicine to reduce the risk of chronic disease and improve health outcomes for her patients.

Franco is also a corporate wellness consultant who conducts wellness counseling and seminars for organizations of every size. She taught sports nutrition to medical students at the Albert Einstein College of Medicine, taught life cycle nutrition and nutrition counseling to undergraduate students at LaGuardia Community College, and precepts nutrition students and interns. She created the sports nutrition rotation for the New York Distance Dietetic Internship program.

She is the chair of the American College of Lifestyle Medicine's Registered Dietitian-Nutritionist Member Interest Group. She is also the treasurer and secretary of the New York State Academy of Nutrition and Dietetics, having previously served in many other leadership roles for the organization, including as past president, awards committee chair, and grant committee chair, among others. She is active in the local Greater New York Dietetic Association and Long Island Academy of Nutrition and Dietetics, too.

Ginger Vieira

Author

Ginger Vieira has lived with type 1 diabetes and celiac disease since 1999, and fibromyalgia since 2014. She is the author of Pregnancy with Type 1 Diabetes, Dealing with Diabetes Burnout, Emotional Eating with Diabetes, and Your Diabetes Science Experiment.

Ginger is a freelance writer and editor with a bachelor's degree in professional writing, and a background in cognitive coaching, video blogging, record-setting competitive powerlifting, personal training, Ashtanga yoga, and motivational speaking.

She lives in Vermont with a handsome husband, two daughters, and a loyal dog named Pedro.

2025-04-23T17:46:55Z

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