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Type 2 Diabetes and Vitamin D, What You Should Know

Type 2 diabetes and vitamin D

Stories about vitamin D are often in the news, and if you have type 2 diabetes, you may wonder whether this nutrient has any special relevance for your health. Well, it does, and here are some things you should know about type 2 diabetes and vitamin D to help you better manage the disease.

What’s special about vitamin D and type 2 diabetes?

Let’s begin by noting that most people do not get enough vitamin D, and there are several reasons for this problem. One is that vitamin D is not found in significant amounts in many common foods, and another is that the best way to get vitamin D is to make it by being exposed to sunlight on a regular basis.

However, items naturally rich in vitamin D (e.g., herring, salmon, cod liver oil) are not on many people’s favorite foods list, so choices such as vitamin D fortified cereals, milk, and soy products are often recommended. Another challenge is that many people do not get the 20 minutes or so of sunlight exposure three to four times a week, year round, to allow their body to make vitamin D.

In these ways, people with type 2 diabetes are like the general population, but there are differences. For example, people with type 2 diabetes have insulin resistance, which means their body has a reduced ability to respond to insulin and thus properly regulate sugar (glucose) levels.

Research shows that vitamin D supplementation can help improve insulin resistance and sensitivity. Insulin resistance also is a risk factor for type 2 diabetes, so improving vitamin D levels may also help prevent the disease.

What a new study says
Type 2 diabetes is associated with a significant risk of complications, including cardiovascular disease, and vitamin D may have an important role in reducing that risk. That was a focus of new research that involved doogh, a yogurt drink popular in the Middle East, but also available in the states and elsewhere.

It’s been shown that low blood levels of vitamin D and oxidative stress (an imbalance between damaging molecules and the body’s ability to detoxify or repair the damage they cause) are associated with diabetic complications. Thus in the current study, the investigators used doogh fortified with vitamin D or calcium and vitamin D to see how it affected individuals with type 2 diabetes.

Ninety patients were randomly assigned to one of three different groups that involved drinking two 250 milliliter (mL) bottles of doogh daily, containing either: 150 mg of calcium per bottle, 150 mg of calcium plus 500 IU vitamin D per bottle, or 250 mg of calcium plus 500 IU vitamin D per bottle.

The authors found that overall, patients who consumed doogh containing vitamin D showed a significant decline in factors associated with oxidative stress. Patients who consumed the doogh with extra calcium did not experience any additional benefit, however.

Another study looked at the effect of taking vitamin D in supplement form at 1,000 IU daily for 12 months. Half of the 47 study participants took vitamin D while the other half took placebo.

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After one year, hemoglobin A1c (HbA1c) levels had declined significantly in patients who had taken vitamin D but had not in those who took placebo. This benefit is significant because the higher a person’s HbA1c level, the greater the risk of developing diabetes complications.

What happens when you consider the impact of vitamin D levels generally in relation to type 2 diabetes? A meta-analysis of 19 studies involving diabetes and measurement of vitamin D revealed the following:

  • Those who had the highest blood levels of vitamin D (greater than 25 nanograms per milliliter, ng/mL) had a 43% lower risk of developing type 2 diabetes than people with the lowest levels (less than 14 ng/mL)
  • Individuals who consumed more than 500 IU of vitamin D daily had a 13% reduced risk of type 2 diabete when compared with those who consumed less than 200 IU daily

Yet another study found more benefits associated with vitamin D and type 2 diabetes, and this one involved women only. In that study, Loyola University Chicago Niehoff School of Nursing researchers evaluated 46 women with type 2 diabetes for an average of 8 years.

Women with insufficient levels of vitamin D were given a weekly supplement of 50,000 IU. After 6 months, their blood levels of vitamin D had risen from an average of 18 ng/mL to an average of 38 ng/mL, their mood had improved, and so had their blood pressure.

The Vitamin D Council recommends a blood level of 50 ng/mL, although many doctors usually say 30 ng/mL is a healthy goal. Most Americans, however, have levels less than 30 ng/mL.

An improvement in blood pressure is especially important since cardiovascular disease is a significant problem among people with type 2 diabetes. In addition, women with type 2 diabetes often have more complications than men, and that is believed to be associated with the greater presence of depression in women, which can interfere with their ability to manage their disease well.

What you can do
If you have type 2 diabetes (and even if you don’t) and don’t know your vitamin D levels, you can ask your doctor to order a blood test to measure the vitamin. It is also possible to order a vitamin D blood test online.

Another option is to discuss your diet and supplement use with your doctor or a registered dietitian, try to determine your daily vitamin D intake (along with sun exposure), and determine if you should take a supplement. You could also begin taking a modest amount of vitamin D (500 to 1,000 IU daily) with your doctor’s knowledge, and see how you respond after several months.

Since your body manufactures vitamin D from sunlight, you can greatly improve your vitamin D status by getting about 15 to 20 minutes of unprotected (no sunscreen) sunlight three to four days a week. Even if you cannot always get this amount of sun exposure, doing it whenever you can, perhaps by taking a short walk during lunch most days of the week, can help.

The bottom line is that vitamin D is an important nutrient for people who want to prevent or who have type 2 diabetes. Boosting your intake or exposure to vitamin D can make a significant, healthy difference in the lives of people who have type 2 diabetes.

Breslavsky A et al. Effects of high doses of vitamin D on arterial properties, adiponectin, leptin and glucose homeostasis in type 2 diabetic patients. Clinical Nutrition 2013; doi:10.1016/j.clnu.2013.01.020.
Mitri J et al. Vitamin D and type 2 diabetes: a systematic review. European Journal of Clinical Nutrition 2011 Sept; 65(9): 1005-15
Nikooyeh B et al. Daily intake of vitamin D- or calcium-vitamin D-fortified Persian yogurt drink (doogh) attenuates diabetes-induced oxidative stress: evidence for antioxidative properties of vitamin D. Journal of Human Nutrition and Dietetics 2013 Jul 5; doi:10.1111/jhn.12142

Image: Morguefile