Vitamin D and Type I Diabetes

Type I Diabetes

Type 1 diabetes is an autoimmune disease. It is a condition where your own immune system attacks certain cells called beta-cells. Beta-cells help you produce a hormone called insulin. You need insulin to help your body manage glucose you get from food and turn it into energy for your body to use. Researchers don’t know what increases your chances of developing type 1 diabetes. Researchers believe that having a family member who has type 1 diabetes might increase your risk of getting type 1 diabetes. Also, viral infections and environmental factors may increase your chances of developing type 1 diabetes, but we need more research to say for sure or understand which factors play a role. Research shows that there is a link between vitamin D and type 1 diabetes. People with high vitamin D intake during their first year of life are less likely to develop type 1 diabetes later in life. Some research also suggests having high vitamin D levels during pregnancy might help prevent type 1 diabetes in their children later in life. However, this research has been observational, meaning we don’t know for sure if getting enough vitamin D prevents type 1 diabetes.

Studies have shown that vitamin D supplementation may help improve insulin sensitivity and help control blood glucose levels in those with type 1 diabetes, though research has been small and inconclusive, so we can’t say for sure if vitamin D helps at all in type 1 diabetes. If you have type 1 diabetes or you are trying to prevent type 1 diabetes and want to take vitamin D, it is unlikely to make your type 1 diabetes worse or cause you any harm, as long as you take less than 10,000 IU per day. However, it’s not proven that it will help your type 1 diabetes. It’s also not proven if taking vitamin D will help you prevent type 1 diabetes. If you have type 1 diabetes, you shouldn’t take vitamin D in place of your treatment medications. Talk to your physician for more advice about taking supplements.

What is type 1 diabetes?

Type 1 diabetes (T1D) is an autoimmune disease. Autoimmune diseases are conditions where your own immune system attacks your body. Your immune system mistakes healthy parts of your body as dangerous and foreign substances. In T1D, your own immune system attacks certain cells called beta-cells. Beta-cells help you produce a hormone called insulin. You need insulin to help your body manage the glucose you get from food and turn it into energy for your body to use. Since these beta-cells are under attack, they can’t produce as much insulin as you need, so you have a hard time controlling the glucose in your body. Because of this, people with T1D need to take injections of insulin. Without these injections, people with T1D can have a build-up of glucose and have symptoms like:

• Excessive thirst
• Lack of concentration
• Blurred vision
• Frequent infections
• Slow-healing wounds

In extreme cases, if a person with T1D does not have access to insulin, they can die¹.

How common is type 1 diabetes?

T1D is a rare form of diabetes and only about 5% of people with diabetes have T1D. It is usually diagnosed in young children. Around 3 million Americans have T1D, and there are an estimated 30,000 people each year diagnosed with T1D. The number of people in the United States with T1D rose by 23% between 2001 and 2009². It’s important to note that T1D is different than the much more common type 2 diabetes (T2D). You develop T2D gradually overtime, likely due to poor lifestyle and dietary habits. On the other hand, T1D happens much more suddenly and is diagnosed usually during childhood, and it is unclear what causes T1D and why some people get it. There are no obvious risk factors in T1D, like poor dietary habits.

What causes type 1 diabetes?

Researchers don’t know exactly what causes T1D. They do know that what happens is that cells called T cells, which are the cells that respond to dangerous substances in your body, start attacking your beta cells. Why they do this, researchers don’t know, but this is what leads to the lack of insulin and the buildup of glucose in your body. It is still unclear what can increase your chances of developing type 1 diabetes. Researchers believe that having a family member who has T1D may increase your risk of developing T1D. Also, viral infections and environmental factors may increase your chances of developing T1D, but we need more research to say for sure or understand which factors play a role¹.

What is the link between type 1 diabetes and vitamin D?

The relationship between T1D and vitamin D is still not fully understood and is still being studied. Researchers believe that vitamin D helps make your immune cells act smarter. This may be important in autoimmune diseases, like T1D, where your immune cells are mistakenly attacking your own body. Researchers are wondering if you get enough vitamin D, if it can help make these cells make less mistakes and help prevent or manage autoimmune diseases better. Vitamin D can attach to receptors on your immune cells, and through chemical signals, help direct the cells to communicate and function properly. Vitamin D receptors are present in important areas involved with T1D. Vitamin D binds to these receptors and helps prevent beta cell death, improve insulin production, and reduce inflammation. However, it’s not clear if these receptors and signals are involved in preventing or treating T1D^3,4.

What does the research say in general about vitamin D and type 1 diabetes?

Preventing type 1 diabetes

Researchers are interested if you get enough vitamin D during early childhood, if you can prevent T1D, or if pregnant mothers get enough vitamin D, they can prevent T1D in their children. Some studies show a link between vitamin D intake and risk of developing T1D. Research has shown that supplementing with vitamin D during the first year of life reduces the risk of developing T1D^3,4. However, most of these studies have been observational, meaning that researchers can’t say for sure whether vitamin D prevents T1D or not. A few studies have looked at the role of vitamin D during different stages of pregnancy and if it might help prevent T1D in children. The results of these studies have been mixed, so researchers can’t say for sure if vitamin D intake during pregnancy can prevent children from developing T1D later in life⁵.

Treating type 1 diabetes

There have only been a few studies looking at vitamin D in the treatment and management of T1D. None of the studies have found vitamin D to be able to treat T1D, but they do suggest a possible role in helping manage some aspects of the disease. These studies suggest that vitamin D plays a role in improving the function of the beta cells, improving insulin production, and managing blood glucose levels, all important things in T1D. Vitamin D may have a role in helping the body produce some of its own insulin when alongside standard insulin treatment^6,7. However, these studies looking at treatment of T1D have had inconclusive results, meaning researchers can’t say for sure if vitamin D helps to treat or manage T1D.

What does recent research say?

Preventing type 1 diabetes

A review of many studies in 2013³ looked at studies on vitamin D and risk of T1D. Out of the studies the researchers reviewed, eight studies looked at vitamin D intake during the first year of life and three studies looked at the effects of vitamin D intake of pregnant women on the risk of T1D in their children years later after they were born. The researchers found:

• Infants who took vitamin D supplements during their first year of life had a significantly reduced risk of T1D compared to those who did not.
• There was no relationship between vitamin D intake during pregnancy and risk of T1D in their children.

All of the studies reviewed were observational, meaning that we don’t know for sure if vitamin D intake during early life can help prevent T1D in children. A study in 2012 in Norway⁵ looked at a large group of women who had given birth between 1992 and 1994. They wanted to know if low vitamin D levels of the mothers during late pregnancy was related to an increased risk of T1D in their children. They found:

• The average vitamin D level of mothers with children with T1D had lower levels compared to women with children without T1D.
• Children born to mothers with vitamin D levels less than 21.6 ng/ml were twice as likely to get T1D compared to women with vitamin D levels above 35.6 ng/ml.

This study was observational however, meaning we can’t say for sure if getting vitamin D during pregnancy protects against T1D. A study done in 2001 in Finland⁴ collected data on more than 10,000 children from 1966 and followed them through to 1998 to see if vitamin D supplementation during the first year of life led to a reduced risk of developing T1D in life. The researchers found:

• Children who took vitamin D supplements, no matter what the dose, had a lower chance of getting T1D compared to those who didn’t take supplements.
• The children who regularly took vitamin D supplements at the recommended daily dose (at the time) of 2,000 IU/day in the first year of life had an 80% lower risk of developing T1D compared to children who took less.

This study was observational, meaning that we can’t say for sure whether vitamin D supplements prevent T1D or not.

Treating type 1 diabetes

A randomized trial in 2010⁶ looked to see if vitamin D has any effect on protecting beta-cell function, a main factor in insulin production and helping manage glucose. The researchers randomized a group of young adults around the age of 18 years old who had recently been diagnosed with T1D to receive either 1,000 IU of vitamin D or a placebo. The researchers followed them for 2 years and found:

• Vitamin D supplementation or vitamin D levels did not help how well the beta-cells functioned.

This study was small and used a low dose of vitamin D, so researchers can’t say for sure whether or not vitamin D can help with beta-cell function in newly diagnosed T1D patients. An experiment in 2010 in Saudi Arabia⁷ looked at a group of teenagers and adults with T1D. They wanted to see if vitamin D and calcium lowered amounts of glycated hemoglobin. High levels of glycated hemoglobin is a common characteristic of T1D and is a sign of poor blood glucose control and higher risk of cardiovascular disease. They looked at 80 vitamin D deficient individuals and gave them 4,000 IU/day of vitamin D and 1,200 mg/day of calcium. They found:

• Those who reached vitamin D levels above 30 ng/ml had much lower glycated hemoglobin levels compared to those who remained below 30 ng/ml. This means that the people with high levels of vitamin D displayed better glucose control than those with lower levels of vitamin D.

However, the researchers couldn’t say for sure if vitamin D and calcium supplementation and having high vitamin D levels helped, since their findings were observational and not compared to a control group.

Key points from the research

• Research has shown that babies with high vitamin D intake during their first year of life are less likely to develop T1D later in life.
• Research has shown that pregnant mothers with high vitamin D levels during pregnancy are less likely to have children that get T1D later in life. However, this research is less strong compared to vitamin D intake during early childhood and infancy.
• Some research has shown that vitamin D may help improve insulin sensitivity and help manage blood glucose in those with T1D, though we can’t say for sure if vitamin D helps at all in T1D.
• The majority of studies that have been done so far have been observational meaning we cannot say for sure if vitamin D is a main factor in the prevention or treatment of T1D.
• More experiments are needed to clearly answer whether vitamin D supplementation can prevent or treat T1D.

What does this mean for me?

Research shows that there is a link between vitamin D and T1D. People with high vitamin D intake during their first year of life are less likely to develop T1D later in life. Some research also suggests having high vitamin D levels during pregnancy might help prevent T1D in their children later in life. However, this research has been observational, meaning we don’t know for sure if getting enough vitamin D prevents T1D. Studies have shown that vitamin D supplementation may help improve insulin sensitivity and help control blood glucose levels in those with T1D, though research has been small and inconclusive, so we can’t say for sure if vitamin D helps at all in T1D. If you have T1D or you are trying to prevent T1D and want to take vitamin D, it is unlikely to make your T1D worse or cause you any harm, as long as you take less than 10,000 IU per day. However, it’s not proven that it will help your T1D. It’s also not proven if taking vitamin D will help you prevent T1D. If you have T1D, you shouldn’t take vitamin D in place of your treatment medications. Talk to your physician for more advice about taking supplements.

References

1. About Diabetes. International Diabetes Federation, 2013. Web. 12 December 2013. https://www.idf.org/about-diabetes
2. Type 1 Diabetes Facts. JDRF, 2013. Web. 12 December 2013. https://medlineplus.gov/ency/article/000305.htm
3. Dong, J. et al. Vitamin D Intake and Risk of Type 1 Diabetes: A Meta-Analysis of Observational Studies. Nutrients 2013;5;3551-3562.
4. Hyppönen, E. et al. Intake of vitamin D and risk of type 1 diabetes: a birth-cohort study. The Lancet 2001;358;1500-1503.
5. Sørensen, I et al. Maternal Serum Levels of 25-Hydroxy-Vitamin D During Pregnancy and Risk of Type 1 Diabetes in the Offspring. Diabetes 2012;61;175-178.
6. Bizzarri, C. et al. No protective effect of calcitriol on beta-cell function in recent-onset type 1 diabetes: the IMDIAB XIII trial. Diabetes Care 2010;33;1962-1963.
7. Aljabri, K. et al. Glycemic changes after vitamin D supplementation in patients with type 1 diabetes mellitus and vitamin D deficiency. Annals of Saudi Medicine 2010;30;454-458.