They were treated at the First Affiliated Hospital of Harbin Medical University between January 2019 and February 2022. Of which, 100 were categorised into the insulin resistance group, while the remaining 62 comprised the non-resistance group.
Within the insulin resistance group, patients were further divided into the conventional treatment and joint treatments groups. The latter received both convention treatment – metformin and insulin pump – plus vitamin D supplementation, in the form of an oral calcium carbonate D3 tablet taken once a day.
All patients were followed up monthly for up to three months and offered personalised diet and exercise advice according to the changes in their blood glucose levels.
To determine the efficacy of vitamin D supplementation, the research team examined the changes of glucose and lipid metabolism indicators before and after this treatment period.
Effects of vitamin D on glucose and lipid metabolism
Analyses of glucose metabolism indicators including 2hPG (2-hour postprandial blood glucose), FBG (fasting blood glucose), and HbA1c (glycosylated haemoglobin) revealed a notable decrease in both treatment groups.
However, the joint treatment group exhibited more significant reductions in all three indicators compared to their conventional treatment counterparts.
Similar trends were observed in lipid metabolism, with the joint treatment group displaying lower TG (triglyceride) and TC (total cholesterol), and a higher HDL-C (high-density lipoprotein-cholesterol) level.
The researchers attribute these findings to vitamin D’s positive effects on insulin resistance, insulin sensitivity, and lipid metabolism regulation.
“By increasing the expression of insulin receptor and promoting glucose transport, vitamin D is helpful to reduce blood glucose level and alleviate the glucose metabolic disorder in T2DM patients,” the researchers wrote.
“In addition, vitamin D also has a regulatory effect on lipid metabolism. It can lower the level of inflammatory factors released by adipocytes, thus improving IR (insulin resistance).”
The study also evaluated the risk factors for insulin resistance in Type 2 diabetes patients and found that Body-Mass Index (BMI), TG, HDL-C, 25-hydroxyvitamin D3 (25(OH)D3), 2hPG, and HbA1c are independent contributors of insulin resistance. This aligned with previous findings.
Significance of vitamin D
In recent years, there has been great interest in the potential benefits of vitamin D supplementation for Type 2 diabetic patients, with a focus on promoting blood glucose control, reducing inflammation, and improving muscle functions.
Past research also underscores the essential role for vitamin D in stimulating insulin secretion and maintaining normal glucose tolerance under physiological conditions.
Vitamin D deficiency is identified as a contributing factor to decreased β cell insulin secretion, thereby exacerbating insulin resistance, and elevating the risk of developing diabetes.
Recent studies revealed that approximately 50 per cent of individuals with Type 2 diabetes suffer from vitamin D deficiency. Moreover, one-third to two-third of these patients experience decreased bon density, heightening the risks of falls, fractures, and mortality, especially among the elderly.
While the findings show promise, researchers acknowledge certain limitations.
Notably, the longevity and effectiveness of vitamin D supplementation require further investigation, urging a focus on long-term efficacy. Also, researchers advise for expanded clinical experiments on a more extensive patient population.
Diabetes as a global health concern
According to the World Health Organization (WHO), there are approximately 425 million diabetes patients globally, a number expected to rise to 700 million by 2045.
Diabetes is a major health challenges as it places a heavy burden on the economic and medical systems.
In the absence of timely and effective treatment, patients face the risk of encountering various complications that greatly compromise both their quality of life and overall lifespan.
The researchers stated: “The study concluded that 25(OH)D3 is an independent risk factor influencing insulin resistance (IR) and supplementation of vitamin D has been shown to improve glucose and lipid metabolism in patients with IR and T2DM.”
Source: World Journal of Diabetes
Effects of vitamin D supplementation on glucose and lipid metabolism in patients with type 2 diabetes mellitus and risk factors for insulin resistance
Authors: Li-Jie Sun, Ji-Xuan Lu, Xin-Yu Li, Tian-Sheng Zheng, Xiao-Rong Zhan