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Information on the latest vitamin D news and research.

Find out more information on deficiency, supplementation, sun exposure, and how vitamin D relates to your health.

Can vitamin D improve insulin resistance during pregnancy?

Insulin is an important hormone produced by the pancreas. With insulin’s help, cells throughout our body absorb glucose – a form of sugar derived from the food we eat – and use it for energy. Insulin resistance is a condition in which the body produces insulin but doesn’t use it effectively. The pancreas will overcompensate and continue to excrete insulin, causing high insulin levels. Insulin resistance can lead to type 2 diabetes, cardiovascular disease, chronic kidney disease, and non-alcoholic fatty liver disease. Past research has shown that insulin resistance often occurs in overweight or obese persons, and also people who have poor diet and exercise habits.

Insulin resistance during pregnancy can lead to gestational diabetes and cardiovascular disease. Past research suggests that low vitamin D levels are correlated with insulin resistance during pregnancy.

In a new study, researchers in Iran were interested in whether different dosages of vitamin D would improve insulin resistance during pregnancy.

The scientists randomized 120 participants to 3 different dosing groups. Group A received 200 IU daily, group B received 50,000 IU monthly (equivalent to 1,666 IU/day), and group C received 50,000 every 2 weeks (equal to 3,333 IU/day). Supplementation began in the 12th week of pregnancy and continued until delivery. The researchers measured vitamin D levels, insulin resistance, and fasting plasma glucose.

The researchers found the following:

  • The mean vitamin D level at baseline was 7.6 ng/ml, with 94.7% of participants below 20 ng/ml.
  • Vitamin D status rose to 17.7 ng/ml in group A, 27.2 ng/ml in group B, and 34.1 ng/ml in group C.
  • Insulin levels rose in all 3 groups. However, insulin levels in group A rose the most.
  • Insulin resistance before and after supplementation was significantly different between groups A and C, with group C showing the most improvement in insulin resistance.
  • Fasting blood glucose and calcium levels were not significantly different in the three groups.

The authors emphasize that although the appropriate vitamin D supplementation dose is unknown, it should be more than the current daily recommended intake.

The authors conclude,

“Our study also demonstrated an appropriate dose of vitamin D supplementation during pregnancy could be 4000 IU vitamin D daily or 50 000 IU every 2 weeks since this dose of vitamin D was able to raise serum 25-hydroxyvitamin D more than 30 ng/ml decreasing insulin resistance.”


Soheilykhah S, et al. The effect of different doses of vitamin D supplementation on insulin resistance during pregnancy. Gynecological Endocrinology, 2013.

  About: Kate Saley

Kate was the Community Coordinator for the Vitamin D Council between 2012-2013. She oversaw the Council’s social media, blog, newsletter and membership base. Kate is currently going to school for occupational therapy.

2 Responses to Can vitamin D improve insulin resistance during pregnancy?

  1. @bacullen, the authors did not specify.