Diabetes and Dietary Supplements: The Case for Vitamin D

No doubt we’ve all heard of diabetes, and the chances are we know at least one person diagnosed with this condition. Over 400 million people have diabetes worldwide with type 2 making up over 90% of the cases.1 The bad news is that the number of individuals in the USA who have diabetes is growing year on year.[2]

So I thought it was about time we looked at some of the evidence regarding diabetes and dietary supplements, particularly, the case for Vitamin D.

What is Diabetes?

Diabetes Mellitus is a disease in which the body’s ability to produce or respond to insulin (the hormone responsible for regulating blood glucose) is impaired resulting in abnormal metabolism of carbohydrates and elevated levels of glucose in the blood. This results in many issues for people who have diabetes, including but not limited to, damage to blood vessels, increased risk of strokes, heart disease, kidney failure, vision loss, and nerve damage. Diabetes also more than doubles the risk of premature death.

Diabetes can be broadly divided into two groups: Type 1 results from the pancreas’s inability to produce enough insulin; Type 2 starts with insulin resistance whereby the cells of the body do not respond to insulin in the normal way. As the disease progresses, the pancreas may also end up producing less insulin.

Can I prevent getting diabetes?

We can’t change some of the risk factors that make us susceptible to developing diabetes such as age, ethnic background, or family history. However, the good news is that we can all make small lifestyle changes such as maintaining a normal body mass, eating a healthy diet, participating in regular exercise. All these positive changes in lifestyle choices can help us reduce our risk of developing Type 2 diabetes.

Diabetes and Dietary Supplements: The case for Vitamin D

There has been some excellent research showing how Vitamin D may be of benefit to diabetics. As we all know Vitamin D is produced in the body following exposure to UVB rays from the sun However studies have shown that up to 90% of people have inadequate levels of vitamin D in the blood to gain from its benefits.[3]

The case for Vitamin D: Type 2 Diabetes

Vitamin D has strong links to insulin resistance and is thought to help the body’s sensitivity to Insulin. Evidence shows that treatment with Vitamin D supplementation can lead to restored insulin secretion and increased expression of the insulin receptor on cells thus increasing insulin sensitivity.[4,5]

A study involving over 80,000 nurses showed an increased risk of type 2 diabetes in those with a low vitamin D status, supplementation with at least 800IU of Vitamin D per day reduced the risk of type 2 diabetes by 33%[6]. Low vitamin D levels have also been shown to be predictive of future development of type 2 diabetes.[7]

The case for Vitamin D: Type 1 Diabetes

The evidence is much more substantial for type 2 diabetes and vitamin D supplementation, however, there are studies that suggest a link between low vitamin D status and type 1 diabetes.

A study in Finland showed that children who took vitamin D supplements daily were 80% less likely to develop Type 1 Diabetes than their peers.[8]


We are learning more and more about vitamin D and its role in diabetes every day, although the mechanism of action is poorly understood there is compelling evidence to show that vitamin D status has a role in the development and treatment of diabetes. Studies support the hypothesis that supplementation with Vitamin D may decrease the incidence of type 1 and type 2 diabetes mellitus.[9]


  1. http://www.who.int/mediacentre/factsheets/fs312/en/
  2. https://gis.cdc.gov/grasp/diabetes/DiabetesAtlas.html
  3. J Clin Endocrinol Metab. 2011 Jul;96(7):1911-30. doi: 10.1210/jc.2011-0385. Epub 2011 Jun 6.
  4. Parekh, Deepal, et al. “Pilot study to evaluate the effect of short-term improvement in vitamin D status on glucose tolerance in patients with type 2 diabetes mellitus.” Endocrine Practice16.4 (2010): 600-608.
  5. von Hurst, Pamela R., Welma Stonehouse, and Jane Coad. “Vitamin D supplementation reduces insulin resistance in South Asian women living in New Zealand who are insulin resistant and vitamin D deficient–a randomised, placebo-controlled trial.” British Journal of Nutrition103.04 (2010): 549-555.
  6. Pittas, Anastassios G., et al. “Vitamin D and calcium intake in relation to type 2 diabetes in women.” Diabetes care29.3 (2006): 650-656.
  7. Forouhi, Nita G., et al. “Baseline serum 25-hydroxy vitamin D is predictive of future glycemic status and insulin resistance.” Diabetes57.10 (2008): 2619-2625.
  8. Hypponen, E., et al. “Intake of vitamin D and risk of type 1 diabetes: a birth-cohort study Lancet 2001 358.” 1500-1503.
  9. Danescu, Liviu G., Shiri Levy, and Joseph Levy. “Vitamin D and diabetes mellitus.” Endocrine35.1 (2009): 11-17.

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