Research Suggests Vitamin D Reduces Blood Sugar In Folks With Diabetes
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December 28, 2025
Image by Nuria Seguí / Stocksy
December 28, 2025
Ranked as the ninth leading cause of mortality globally and contributing to more than 1 million annual deaths, it’s no wonder that the prevention and management of Type 2 diabetes, blood glucose spikes, and insulin resistance is a high priority in public health.
Glucose comes directly from our diet, so nutrition and other lifestyle habits play a massive role in the symptoms and pathways associated with Type 2 diabetes. And researchers have discovered that one essential vitamin plays a larger role in promoting healthy blood sugar levels and insulin sensitivity than previously recognized.
How vitamin D impacts blood sugar balance
In a systematic review and meta-analysis of randomized controlled trials (RCTs) from BMC Endocrine Disorders, scientists investigated the theorized anti-diabetic properties of vitamin D—such as its ability to regulate insulin secretion (i.e., insulin sensitivity), modulate healthy inflammatory responses, and downregulate elevated parathyroid hormone levels.
Researchers looked at 46 RCTs that consisted of 2,164 intervention participants and 2,149 placebo controls. They found that increased vitamin D intake reduced the following measurements in participants with Type 2 diabetes:
Significantly reduced fasting plasma glucose (FPG), a measurement used to detect short-term blood glucose.
Slightly reduced hemoglobin A1c (HbA1c), a measurement used to detect long-term blood glucose.
Significantly reduced homeostasis model assessment—insulin resistance (HOMA-IR), a robust tool for the assessment of insulin resistance.
Findings also suggest that upping one’s vitamin D intake leads to significant reductions in FPG and HbA1c for individuals with vitamin D deficiency but not in participants with vitamin D insufficiency or sufficiency.
How to achieve & maintain healthy vitamin D levels
The problem? Reaching and sustaining sufficient vitamin D status is much easier said than done. In fact, 29% of U.S. adults1 are deficient in vitamin D.
You see, foods with vitamin D don’t have large enough amounts to make a dent in vitamin D levels—especially in individuals who are already deficient. “What about sunshine?” you may ask. Unfortunately, sunlight isn’t a reliable source of vitamin D production for most people either, as it’s influenced by a number of factors (e.g., age, biological sex, latitude, climate, time of year, skin tone, sunscreen use, and how much skin is exposed to sun).
The optimal manner to effectively reach and sustain healthy vitamin D status (which leading wellness experts agree is a blood serum measurement of 50 ng/ml or higher) is through daily vitamin D supplementation.
The takeaway
Science suggests that optimizing daily vitamin D intake can help individuals with Type 2 diabetes (especially those with vitamin D deficiency) improve their insulin sensitivity and lower their blood sugar levels.
