A study in Nutrients 2024, based on 20 clinical trials of nearly 15,000 adults with diabetes and pre-diabetes, found that vitamin D supplementation was associated with improvements in several metabolic markers including glycosylated haemoglobin, LDL cholesterol, triglycerides and markers of insulin resistance. The changes were generally modest, but consistent, and were obtained with varying doses of vitamin D over an average of 17 months.
For people with impaired glucose control, these results suggest that maintaining adequate vitamin D status can accompany improvements in glycaemic, lipid and inflammatory profiles, as part of a comprehensive approach that includes diet, movement and medication where appropriate. For those who do not yet have diabetes but have risk factors, the message is clear: taking care of vitamin D levels is part of maintaining a more stable metabolism.
Study shows vitamin D is associated with improved glucose and lipid markers
The authors conducted a systematic review and meta-analysis, i.e. pooled data from 20 randomised clinical trials comparing vitamin D versus placebo or other interventions in people with type 1 diabetes, type 2 diabetes or pre-diabetes. Overall, they analysed 14,831 participants, with a mean age of about 51 years and an average follow-up of just over a year.
Vitamin D supplementation was associated with a slight but significant reduction in glycosylated haemoglobin, a marker that summarises average glucose over the past three months, and with decreases in insulin resistance as measured by the HOMA-IR index. Reductions in LDL cholesterol, triglycerides and C-reactive protein were also observed, along with an increase in HDL cholesterol. In people with pre-diabetes, the proportion returning to glucose values considered normal also increased.
The researchers rate the overall quality of the evidence as low or very low on several variables, because of heterogeneity between studies and differences in dose, duration and populations. Still, the overall pattern is consistent – when a vitamin D deficit is corrected, a better metabolic profile tends to be seen.
How vitamin D relates to insulin, cholesterol and inflammation
Vitamin D is known for its role in calcium absorption and bone health, but it also acts as a hormone that influences the pancreas, muscle, fat tissue and the immune system. In the beta cells of the pancreas, which produce insulin, vitamin D is involved in calcium entry, a key step in the proper release of insulin.
In insulin-responsive tissues, such as muscle and liver, vitamin D modulates the expression of the insulin receptor and pathways related to glucose and lipid metabolism. This is reflected in markers such as the HOMA-IR index, which estimates insulin resistance, and in parameters such as triglycerides and LDL cholesterol, which are part of cardiometabolic risk.
In the field of inflammation, vitamin D regulates the production of cytokines, molecules that can amplify or slow down chronic inflammatory processes. The study picked up changes in C-reactive protein and interleukins such as IL-6, which are indirect indicators of systemic inflammatory status. Although not all changes were statistically significant, the overall trend was towards less inflammation.
Daily habits that help keep vitamin D and metabolism in balance
The first pillar of good vitamin D status is prudent sun exposure. Spending time outdoors with uncovered arms and legs, avoiding peak radiation hours, promotes skin vitamin D synthesis. The amount of time needed depends on skin tone, latitude and season.
In the diet, natural sources of vitamin D are limited, especially fatty fish such as salmon, mackerel or sardines, and some fortified products. Integrating these foods into a diet based on vegetables, fruit, legumes, nuts and olive oil helps to improve the overall glycaemic and lipid profile.
Regular movement, both aerobic exercise and strength work, improves insulin sensitivity and helps to reduce triglycerides and visceral fat. Sufficient rest and stress management also influence hormones that are related to metabolism, such as cortisol. In people with diabetes or pre-diabetes, these habits are combined with medical treatment and monitoring of analytical parameters.
How Nutribiolite’s OMEGA 3 EPA 400 mg and DHA 300 mg supplement integrates vitamin D in a formula designed for metabolic and cardiovascular balance
The Nutrients study focuses on isolated vitamin D, administered in various forms such as drops, capsules or tablets. Nutribiolite OMEGA 3 EPA 400 mg and DHA 300 mg incorporates vitamin D as part of a broader formulation, combining long-chain omega-3 fatty acids with this fat-soluble vitamin.
Vitamin D in this context is supported by a fat matrix rich in EPA and DHA, the two major marine omega-3 fatty acids. This combination makes physiological sense, vitamin D is better absorbed in the presence of fat, and omega-3s are involved in modulating inflammation, cell membrane fluidity and lipid profile.
The meta-analysis findings support that when a vitamin D deficient or deficient state is corrected, improvements in parameters such as glycosylated haemoglobin, LDL cholesterol, triglycerides and inflammatory markers are observed in adults with diabetes and pre-diabetes. In a person who already takes care of their diet and physical activity, a formulation that provides vitamin D together with omega 3 may be suitable as additional support for these same metabolic axes, always understood as a nutritional supplement.
OMEGA 3 EPA 400 mg and DHA 300 mg is aimed at adults who wish to take care of their cardiovascular and metabolic health through nutrients with a well-described role in human physiology. The presence of vitamin D in the formula is in line with the evidence linking it to glycaemic control, lipid profile and inflammation, while omega-3s contribute their own action on triglycerides, cell membranes and inflammatory balance.
A supplement with marine omega-3 and vitamin D, designed for adults caring for their cardiovascular and metabolic health as part of a healthy lifestyle.
What we can take away from this study for everyday life
Meta-analysis in adults with diabetes and pre-diabetes suggests that vitamin D, when provided in sufficient amounts, is associated with improved performance on markers of glucose, lipids and inflammation. The changes are modest, but are in addition to the effects of diet, exercise and medical treatment.
For a person seeking to take care of their cardiometabolic health, the central message is twofold: maintain habits that support good vitamin D status and, when considering supplementation, prioritise formulations that integrate nutrients with clear physiological functions, such as omega-3s and vitamin D itself. All of this is part of an overall strategy that is built on a day-to-day basis with decisions about movement, rest and nutrition.
This content is informative and does not replace the advice of a health professional.
Frequently asked questions
What did the study on vitamin D in people with diabetes and pre-diabetes show?
The meta-analysis found that vitamin D supplementation was associated with slight reductions in glycated haemoglobin, insulin resistance, LDL cholesterol, triglycerides and some inflammatory markers, along with an increase in HDL cholesterol. The effects were modest, but consistent over time.
Why vitamin D is relevant to glucose metabolism
Vitamin D is involved in the function of beta cells in the pancreas, which produce insulin, and in the sensitivity of tissues to this hormone. Adequate vitamin D status is therefore associated with better glucose control and more favourable markers of insulin resistance.
How vitamin D relates to lipids and cholesterol
In the studies reviewed, vitamin D was associated with decreases in LDL-cholesterol and triglycerides and a slight increase in HDL-cholesterol. These changes are interpreted as an improvement in lipid profile, especially relevant in people at high cardiovascular risk.
How OMEGA 3 EPA 400 mg and DHA 300 mg fits in with the evidence on vitamin D
OMEGA 3 EPA 400 mg and DHA 300 mg incorporates vitamin D into a formula rich in marine omega-3 fatty acids. The study reinforces the value of including vitamin D in strategies to support glycaemic, lipid and inflammatory balance, and in this supplement it is combined with EPA and DHA, which are also involved in cardiovascular and metabolic health.
For what type of person might a supplement with omega-3 and vitamin D make sense?
It may suit adults who already take care of their diet, are physically active and want additional cardiovascular and metabolic support through nutrients with well-described functions such as omega-3s and vitamin D. It is always integrated within a healthy lifestyle and professional follow-up when there are previous diagnoses.
