Vitamin D And Diabetes Mellitus: The Powerful Link

Vitamin D and Diabetes Mellitus hold a strong link, apparently because of the role of vitamin D in glucose metabolism. Vitamin D is involved in a huge number of biochemical processes, ranging from promoting calcium absorption, reducing inflammation and modulating neuromuscular and immune function.

Vitamin D deficiency is more commonly found in the elderly and people who stay indoors. It is believed to contribute to several health conditions, especially bone disorders and fragility. The less commonly known vitamin D associated health issues, include diabetes. As of today, the science is less clear about the exact possible connection between Vitamin D and Diabetes Mellitus. However, research so far has shed enormous light on the possible manners in which vitamin D affects blood sugar.

Vitamin D and Diabetes Mellitus

Studies have shown that people with decreased levels of vitamin D are at a higher risk of developing type 2 diabetes.

But how does vitamin D actually help in managing blood sugar levels?

Vitamin D And Diabetes Mellitus: The Connection

Vitamin D plays an important role in insulin sensitivity, which is essential for regulating blood glucose levels. Additionally, vitamin D also holds anti-inflammatory properties, which can help reduce insulin resistance and improve overall blood glucose control.

Maintaining adequate levels of vitamin D can be a challenge, especially for those who spend most of their time indoors or live in areas with limited sun exposure. Luckily, there are ways to increase your vitamin D levels through dietary supplementation.

This article explores the powerful link between vitamin D and diabetes and can also help you optimize your vitamin D intake to better manage your blood sugar levels.

Does Vitamin D affect Blood Sugar?

Vitamin D plays a crucial role in blood sugar regulation by improving insulin sensitivity. Insulin is a hormone produced by the pancreas that allows glucose to enter the cells and be used for energy. In people with diabetes, the body either does not produce enough insulin or does not use it effectively, leading to high blood sugar levels.

Research has shown that vitamin D helps the body use insulin more effectively, improving insulin sensitivity. This means that the cells become more responsive to insulin, allowing glucose to enter and be used for energy. By improving insulin sensitivity, vitamin D helps regulate blood sugar levels and reduces the risk of developing diabetes.

Additionally, vitamin D has been found to have anti-inflammatory properties, which can help reduce insulin resistance. Inflammation is believed to play a role in the development of insulin resistance, and by reducing inflammation, vitamin D can help improve insulin sensitivity and blood sugar control.

Role of Vitamin D in Blood Sugar Regulation

There is growing evidence that vitamin D deficiency could be one possible factor in the development of both type 1 and type 2 diabetes. Studies so far have indicated that vitamin D treatment improves glucose tolerance and insulin resistance. On the other hand, Vitamin D deficiency leads to reduced insulin secretion. Supplementation with vitamin D has been shown to restore insulin secretion in lab animals. Researchers have found an indirect effect of vitamin D on insulin secretion, potentially through a calcium effect on insulin secretion. Vitamin D contributes to normalization of extracellular calcium levels, thus ensuring normal calcium flux through cell membranes. This explains why low vitamin D may diminish calcium’s ability to affect insulin secretion.

Other potential mechanisms in the link between vitamin D and diabetes include improving insulin action by stimulating expression of the insulin receptors. This enhances insulin responsiveness for glucose transport. It helps to improve systemic inflammation by a direct effect on cytokines.

Vitamin D and Type 1 Diabetes Mellitus

Type 1 diabetes is characterized by an autoimmune attack on the pancreatic beta cells. Because vitamin D influences both the immune system and beta-cell function, many researchers have searched for a connection between vitamin D and type 1 diabetes.

Several recent studies have shown that vitamin D supplementation can have positive effects on people with type 1:

Vitamin D and Type 1 Diabetes Studies

Observational studies have suggested that low vitamin D status may be associated with an increased risk of developing type 1 diabetes. This can be easily proved in case of greater incidence of type 1 diabetes related to geographic variation, with locations at higher latitudes showing higher numbers. This can be the possibly owing to less sunshine and, therefore, lower levels of vitamin D.

Hypponen et al. of Northern Finland conducted a cohort study. They collected data during first year of age, on 10,821 children regarding vitamin D supplementation dose and presence of rickets as it is related to the development of type 1 diabetes. Their findings showed significant and astounding results. The children who were given 2,000 IU of vitamin D daily were 80% less prone to develop type 1 diabetes. This suggests that it may be crucial for children to take vitamin D supplementation during their first year of age to avoid the development of type 1 diabetes.

Another similar study conducted by Zipitis et al. demonstrated that vitamin D supplementation in early childhood decreased the risk of development of type 1 diabetes by 29% compared to children who did not receive vitamin D supplements. Interestingly, the researchers found evidence suggesting a dose-response effect.

The destruction of β-cells usually begins in infancy or in early childhood and continues until type 1 diabetes is diagnosed. Starting vitamin D supplementation soon after birth may play a protective strategy against the development of type 1 diabetes.

Vitamin D Supplementation during Pregnancy & Lactation

Gregory et al. suggested that pregnant women and nursing mothers should take vitamin D supplements to ensure that their vitamin D serum levels are optimal. Their research showed that adequate vitamin D status in mothers quite well helped to reduce the development of type 1 diabetes in their children.

Vitamin D for Diabetes Prevention

This research group reasoned that because vitamin D is a powerful modulator of the immune system, it becomes apparent that vitamin D could play a role in preventing type 1 diabetes.

However, studies to know the precise dose and duration of vitamin D supplementation in infants and children are lacking. Currently, 400 IU of vitamin D3 supplementation is recommended for in all infants until enough of formula, milk, or other food sources are given to sufficiently provide 400 IU per day.

Currently available research evidence supports that maintaining adequate vitamin D levels during pregnancy, nursing, infancy, and childhood may help prevent type 1 diabetes. However, it is still not exactly known whether the genetics of type 1 diabetes puts individuals at risk for vitamin D deficiency or whether the vitamin D deficiency puts individuals at risk for type 1 diabetes.


All these studies may sound encouraging, but they are considered preliminary stage studies. Experts have not yet firmly agreed that vitamin D supplementation can directly lead to better diabetes management.

Also, the studies to support that vitamin D supplementation could improve the treatment of type 1 diabetes after diagnosis, are still lacking.

It’s possible that a lack of vitamin D can contribute to the development of type 1 diabetes in the first place. Epidemiological studies have also suggested that decreased levels of vitamin D are associated with the risk of developing type1 diabetes. But the science on this link is still not clear enough to establish a firm connection, a February 2021 randomization study suggested that the association could be due to confounding factors.

Vitamin D and Type 2 Diabetes Mellitus, and Pre-diabetes

So far, the research has hinted a more clear relationship between type 2 diabetes and vitamin D. This can also be due to the increased occurrence of type 2 diabetes and thus the bigger number of sample data to study. The researchers are still working further to be able to get more specific results.

Vitamin D Deficiency in Diabetes

Numerous studies have demonstrated that patients of obesity, metabolic syndrome, and type 2 diabetes, are more prone to be deficient in vitamin D, as compared to healthy people. Vitamin D levels are also associated with both insulin sensitivity and beta cell function. Vitamin D3 may also be able to help improve insulin secretion.

A number of research studies have evaluated the effects of vitamin D supplementation in patients of both pre-diabetes and type 2 diabetes. The results stated that, there appears to be a weak yet potentially significant relationship between vitamin D supplementation and improved type 2 diabetes management.

Vitamin D & Type 2 Diabetes Study

An observational study from the Nurses Health Study that included 83,779 women, above 20 years of age, found an increased risk of type 2 diabetes in individuals with low vitamin D status. A daily intake of more than 800 IU of vitamin D and 1,000 mg of calcium, in combination, reduced the risk of type 2 diabetes by 33%.

Another study published in the Journal of Investigative Medicine found that vitamin D supplementation improved insulin sensitivity and reduced the risk of developing type 2 diabetes in people with prediabetes.

A multiethnic study on 712 individuals indicated that vitamin D is significantly correlated to insulin resistance and beta-cell function. The results concluded that low vitamin D levels may play a significant role in developing type 2 diabetes.

A literature review of 24 individual studies stated that vitamin D supplementation was found to be associated with reduced HbA1c levels, especially in individuals who had vitamin D deficiency before beginning the experiment.

second review stated that higher levels of vitamin D and vitamin D supplementation were both found to be associated with a lower risk of developing type 2 diabetes.

Although, the level of the type 2 diabetes risk reduction is “relatively small,” it is possible that patients with type 2 diabetes and pre-diabetes can benefit from vitamin D supplementation.

Vitamin D Supplementation

The easiest and best way to safely boost your vitamin D levels is to get sunshine. The skin produces a generous amount of this vitamin D when it is exposed to the sun’s UVB rays. The amount of sunlight you might need varies widely based on certain factors like location, season, skin color and the amount of skin you exposure.

How to Safely Get Vitamin D From Sunlight?

Vitamin D Foods For Diabetic Patients

Vitamin D can also be found in some food sources like fatty fish, some organ meats, egg yolks and fortified products like milk.

Lastly, the easiest and quickest way is to take vitamin D supplements. Current Recommendations suggest supplementing with 400-800 international units per day. In some circumstances your doctor might prescribe a higher dose if you are found severely deficient.

However, it’s important to remember that vitamin D supplementation should be done under the guidance of a healthcare professional, as excessive intake can lead to toxicity. Regular monitoring of vitamin D levels is also recommended to ensure optimal blood levels are maintained.

Summary and Conclusion

Vitamin D holds a complex relationship with the metabolic system. People with diabetes are often found with lower levels of vitamin D. Although the role of vitamin D in helping regulate blood glucose remains poorly understood, vitamin D status still appears to play a role in the development and treatment of diabetes. According to Danescu et al., “both animal and human studies support that adequate vitamin D supplementation may decrease the incidence of type 1 and possibly also of type 2 diabetes mellitus and may improve the metabolic control in diabetes. However, the exact mechanisms are not yet clear enough and thus need further investigation.”


Can Vitamin D reverse diabetes?

Both animal and human studies have proved that vitamin D improves the blood sugar levels in diabetes. More studies are needed to confirm if vitamin D can totally reverse diabetes.

Can vitamin D cause low blood sugar?

Intake of vitamin D supplements led to a marginally significant reduction in fasting blood glucose.

Can vitamin D supplementation cause toxicity?

Vitamin D toxicity is a rare but potentially serious condition that occurs when you have excess amounts of vitamin D in your body. Vitamin D toxicity is usually caused by large doses of vitamin D supplements — not by diet or sun exposure.
The main consequence of vitamin D toxicity is a buildup of calcium in your blood (hypercalcemia).

My name is Amanpreet Kaur Samra. M.S. Biochemistry. I'm the founder and writer of this blog. I have been teaching Biochemistry for a good number of years. I started this blog because I have always been very passionate about writing, in particular about Nutrition and Healthy Weight Loss.

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