By: Rachel Namery, MS Nutrition Science
An Interesting Role of Vitamin D in Glucose Homeostasis
A recent study suggests that higher levels of vitamin D are associated with a decreased risk of glucose imbalance among non-diabetic Southwest Chinese adults.
Type II diabetes is a metabolic disease that is far too prevalent across the globe. For example, in 2013, half of the population in China was prediabetic; a condition in which fasting glucose levels are between 100 -125. Individuals with prediabetes are at a greater risk of developing type II diabetes. Unlike most diabetes, pre-diabetes is reversible if caught early and fixed with health lifestyle changes. Rates of type 2 diabetes have increased markedly since 1960 in parallel with obesity. As of 2015 there were approximately 392 million people diagnosed with the disease compared to around 30 million in 1985, a ten-fold increase in 30 years. Interestingly, those born in the summer have a lower risk of developing type II diabetes. Vitamin D status plays a crucial role in helping prevent many diseases including some cancers, multiple sclerosis, cardiovascular disease, osteoporosis and diabetes. Studies have shown a direct correlation between vitamin D deficiency and insufficiency with obesity and type II diabetes. Doctors and scientists theorize this relationship is because of vitamin D’s ability to help regulate pancreatic beta-cell function, insulin action and inflammation. With so much compelling research on vitamin D, it is becoming clearer that levels need to be monitored as a part of a proactive approach to one’s health.
Interesting research on vitamin D and glucose homeostasis
A recent large cross-sectional study examined whether a higher serum vitamin D level was
associated with better glucose homeostasis among 1,514 healthy adults between the ages of 25 and 65 (mean age of 48.74) without diabetes. The sample was broken down into three groups: one was the group of people who were deficient (25(OH)D<20 ng/ml) in vitamin D, two was the group that was insufficient (25(OH)D between 20-30 ng/ml) and group three were those with 25(OH)D >30 ng/ml. The researchers measured the participants 25(OH)D levels, fasting plasma glucose, hemoglobin A1C, (HbA1c), fasting insulin, the homeostatic model assessment 2-insulin resistance (HOMA2-IR) and odds of having prediabetes. The researchers used these measures to define glucose homeostasis. Other anthropometric measures and demographics were recorded as well.
What were the outcomes? This study suggests that adequate vitamin D levels (25(OH)D >30 ng/ml) were correlated with healthier glucose homeostasis. In addition, the researchers found a significant inverse association between 25(OH)D and fasting insulin (p = 0.016), insulin resistance (p = 0.016) and HBA1c (p =0.0003). That is, the higher one’s vitamin D, the less likely one has diabetic markers. The study also suggests lower levels of vitamin D are associated with prediabetes risk. Adults in with the highest 25(OH)D had a 12.4% lower fasting insulin (p = 0.0007), 12.3% lower HOMA2-IR (p = 0.0007) and 2.2% lower HbA1c (p = 0.0001) compared to those with the lowest vitamin D levels. Also, the researchers observed a 32% lower odds of prediabetes in the adults in the highest tertile of serum vitamin D compared to those in the lowest tertile.
The researchers concluded,
“Higher serum 25(OH)D level is associated with decreased risk of impairment of glucose
homeostasis among adults without diabetes in Southwest China. Further studies are
warranted to determine the role of vitamin D in glucose homeostasis.”
These findings support past studies on the topic in both non-diabetics and diabetics. For example, a meta-analysis including 71 studies that evaluated 25(OH)D status in both diabetic and non-diabetics found a significant inverse association between vitamin D status and type II diabetes. They also found a correlation between vitamin D deficiency and higher fasting plasma glucose in both diabetics and non-diabetics.
After consulting with your doctor and determining your vitamin D status you could possibly implement more sun exposure or supplementation to bring your levels back to an optimal range which may help with glucose homeostasis.
Danting.Li. et al. Higher Serum 25(OH)D level is associated with decreased risk of impairment of glucose homeostasis: data from SouthWest China. BMC Endocrine