When was the last time you checked your vitamin D levels? A question worth pondering.
For decades, Vitamin D has long been considered merely a “sunshine” nutrient, and disregarded as a vitamin needed exclusively for its skeletal functions. This has immensely contributed to an ‘Ignored Epidemic’ scenario, which has indirectly given rise to many lifestyle diseases. According to an article published in The International Journal of Health Sciences (2010), over a billion people worldwide are estimated to be deficient in vitamin D. This has led researchers to link vitamin D deficiency to numerous metabolic disorders. The most relevant one being Vitamin D deficiency may contribute to impaired glucose or blood sugar regulation and increased diabetes risk, including Type 2 Diabetes Mellitus. Current evidence suggests Vitamin D status may influence glucose metabolism, though diabetes development is multifactorial.
On behalf of MedBound Times, we connected with Dr Aby Lukose, working as a Family Physician and Diabetologist in Kochi, for his expert advice on the role of Vitamin D in glycemic regulation.
Vitamin D may help improve glycemic control in patients with T2DM. It may improve insulin sensitivity and support pancreatic beta-cell function. I observed an HbA1c reduction of 1.4% in one of my patients with T2DM and insufficient vitamin D after supplementation for 3 months.Dr Aby Lukose, MBBS, C.DIAB, PGDFM (CMC Vellore)
Vitamin D and its many roles
Vitamin D3 (cholecalciferol) is a fat-soluble vitamin that is converted in the liver and kidneys into its hormonally active form, calcitriol.
Sunlight after penetrating the skin triggers Vitamin D production under the skin surface.
The major functions of Vitamin D are:
Skeletal Functions: Along with calcium helps in bone mineralisation, growth and remodelling
Muscular Functions: Helps in muscular movements
Immune system support: Modulates immune response to viruses and pathogens
Cell Regulation and Inflammation: Regulates inflammation and cellular repair mechanisms including autophagy
Nervous System: Acts as a neuroprotectant that supports brain development and function (6)
Clinical Significance
Vitamin D deficiency is highly prevalent worldwide
Low vitamin D levels are associated with insulin resistance
Screening may benefit individuals with diabetes and prediabetes
Supplementation may support glycemic control when medically indicated
The ‘Pancreatic Guard’: Vitamin D as a Metabolic Hormone
The Pancreas, the large ‘tadpole’- shaped endocrine organ, helps in the regulation of blood glucose level by producing a hormone called insulin. It has pancreatic beta cells that contain vitamin D receptors. Just like a lock and key, the receptors are the lock, and vitamin D is the key.
These receptors, or VDR, get activated with sufficient vitamin D, which leads to adequate production of insulin that helps in regulating the blood sugar levels. VDR activation also helps the pancreatic β cells from cell death and reduces inflammation which in turn helps in the proper functioning of these cells.
Two-thirds of my diabetic patients were found to have vitamin D deficiency. Supplementation along with oral hypoglycemic agents may improve glycemic control to a moderate extent. We routinely check vitamin D levels in newly diagnosed diabetes patients.Dr Aby Lukose, MBBS, C.DIAB, PGDFM (CMC Vellore)
Pre Diabetic Indicator
Vitamin D is crucial in the development and progression from a pre-diabetic state to type 2 diabetes mellitus.
Research shows that people with low vitamin D levels are more likely to have prediabetes, which can increase the risk of developing type 2 diabetes.
Insufficient Vitamin D due to low sun exposure or low intake through diet may reduce insulin production in the pancreatic cells, leading to high levels of blood sugar in the body.
Dr. Lukose added, “Vitamin D supplementation in prediabetics found to prolong the onset of diabetes by improving insulin sensitivity and reducing the chances of inflammation.”
Vitamin D Supplementation
Vitamin D is a fat-soluble vitamin. It can be supplemented through:
Diet
Supplements
Adequate sunlight exposure (cutaneous synthesis)
Dietary sources include fish liver oil, fatty fish, milk, mushrooms, egg yolks, liver, fortified cereals. Evidence has shown that diet rich in vitamin D reduces HbA1c (blood glucose indicator) in diabetic patients.(5)
Vitamin D supplementation is generally recommended with daily ranges of 400-800 IU (10-20mcg), depending on age and individual requirements. Vitamin D3 supplements are preferred over vitamin D2. Taking them with meals containing fat may help with better absorption.
Get your vitamin D levels tested and start supplementation only after consulting a doctor.
The Recommended Daily Intake (RDI) according to The Food and Nutrition Board at the National Academies of Sciences, Engineering and Medicine includes:
Infants and children: 400-600 IU (10mcg - 15mcg)
Adults: 600-800 IU (15mcg - 20mcg)
Pregnant and breastfeeding: 600 IU (15mcg)
Sunlight is the primary natural source of vitamin D. Just 20-30 minutes of morning sunlight exposure several times a week produces an adequate amount of the vitamin. However key factors affecting production are skin melanin (darker the skin, longer sun exposure required), age (as age advances, the skins ability to produce vitamin D decreases), location (region with more sunlight all year around helps in more vitamin d production compared to regions with less sunlight) and season (summer gives more sun exposure compared to winter or rainy season).
The Takeaway
Vitamin D has a multifaceted role in the prevention and management of diabetes mellitus. However, further studies would be needed to convert these findings into universal clinical instructions.
In today’s hectic life, sedentary indoor lifestyles contribute significantly to vitamin D deficiency, often causing its importance to go unnoticed.
Always keep in mind that, before taking any kind of supplementation, it is advisable to seek advice from a qualified healthcare professional. Testing your blood levels of vitamin D will help determine the accurate dosage.
Since further studies are still ongoing to establish a stronger link between Vitamin D and blood sugar control, vitamin D supplements cannot be used as a standalone treatment and should be considered as a complementary factor. In addition, lifestyle modification, stress management, a balanced diet, and regular outdoor activities for children and adults can significantly improve blood sugar control, along with regular checkups and routine monitoring under medical guidance.
REFERENCES
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Lee J, Lee YJ, Kim Y. A high prevalence of prediabetes and vitamin D deficiency are more closely associated in women: results of a cross-sectional study. J Int Med Res. 2021 Jul;49(7):3000605211033384. doi: 10.1177/03000605211033384. PMID: 34334004; PMCID: PMC8326633.
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Chen W, Liu L, Hu F. Efficacy of vitamin D supplementation on glycaemic control in type 2 diabetes: An updated systematic review and meta-analysis of randomized controlled trials. Diabetes Obes Metab. 2024 Dec;26(12):5713-5726. doi: 10.1111/dom.15941. Epub 2024 Oct 2. PMID: 39355942.
Sunil J. Wimalawansa, “Non-Musculoskeletal Benefits of Vitamin D,” Journal of Steroid Biochemistry and Molecular Biology 175 (January 2018): 60–81, https://doi.org/10.1016/j.jsbmb.2016.09.016