According to Gram Research analysis, children with type 1 diabetes have significantly lower vitamin D levels than healthy children, with much higher rates of vitamin D deficiency and insufficiency. A 2026 study of children in China found that multiple factors—including age, season, disease duration, and blood sugar control—influence vitamin D levels in children with diabetes. While this connection suggests vitamin D deficiency may play a role in type 1 diabetes, researchers emphasize that more studies are needed to understand whether low vitamin D contributes to diabetes development or if treating deficiency improves outcomes.
A new study from China looked at vitamin D levels in children with type 1 diabetes and found they had significantly lower levels than healthy kids. Researchers examined medical records from over 1,000 children between 2017 and 2023, comparing those with diabetes to those without. The study discovered that vitamin D deficiency was much more common in children with type 1 diabetes, and several factors—including age, season, how long they’ve had diabetes, and their blood sugar control—affected their vitamin D levels. While the study suggests vitamin D deficiency might play a role in type 1 diabetes development, researchers say more research is needed to fully understand this connection.
Key Statistics
A 2026 research article analyzing medical records from over 1,000 children in China found that children with type 1 diabetes had significantly lower vitamin D levels and substantially higher rates of vitamin D deficiency compared to healthy children.
According to research reviewed by Gram, age, admission season, disease duration, sex, place of residence, and blood sugar control (HbA1C levels) were all identified as statistically significant factors affecting vitamin D levels in children with type 1 diabetes.
The 2026 study found that vitamin D insufficiency or deficiency was more prevalent across all subgroups of children with type 1 diabetes when compared to corresponding healthy control groups, regardless of age, sex, or residence.
Research shows that children with type 1 diabetes tested during winter and spring months had lower vitamin D levels than those tested during summer and fall, highlighting the seasonal influence on vitamin D status in this population.
The Quick Take
- What they studied: Whether children with type 1 diabetes have lower vitamin D levels than healthy children, and what factors affect those levels.
- Who participated: Children with type 1 diabetes treated at a hospital in China between 2017-2023, compared with healthy children who came for regular check-ups during the same time period.
- Key finding: Children with type 1 diabetes had significantly lower vitamin D levels and much higher rates of vitamin D deficiency compared to healthy children. Multiple factors influenced these levels, including age, season, how long they’ve had diabetes, and their blood sugar control.
- What it means for you: If your child has type 1 diabetes, getting their vitamin D levels checked and ensuring adequate vitamin D intake may be important. However, this study shows a connection but doesn’t prove vitamin D deficiency causes diabetes—more research is needed before making major treatment changes.
The Research Details
This was a retrospective study, meaning researchers looked back at medical records that were already collected rather than following children forward in time. They gathered information on children with type 1 diabetes who visited a hospital in China between January 2017 and December 2023, and compared them to healthy children who had regular check-ups during the same period.
The researchers measured vitamin D levels in blood samples and looked at how many children had vitamin D deficiency (very low levels) or insufficiency (low but not critically low levels). They also examined how different factors—like the child’s age, sex, where they lived, what season they were tested, how long they’d had diabetes, and their blood sugar control—related to their vitamin D levels.
This approach allowed them to identify patterns and connections between vitamin D and type 1 diabetes, though it cannot prove that one causes the other.
Understanding whether children with type 1 diabetes have vitamin D problems is important because vitamin D plays a role in immune system function and blood sugar control. If vitamin D deficiency is common in these children, doctors might want to check and treat it as part of their diabetes care. This type of study helps identify potential health issues that doctors should pay attention to.
The study’s main strength is that it included a large number of children over a 7-year period, giving researchers lots of information to analyze. However, the researchers themselves noted important limitations: because they looked at existing medical records rather than following children prospectively, they couldn’t control for all factors that might affect vitamin D levels. Some important information that might explain the results was missing from the records. The study shows a connection between vitamin D and type 1 diabetes but cannot prove cause-and-effect.
What the Results Show
Children with type 1 diabetes had significantly lower vitamin D levels compared to healthy children. The proportion of children with vitamin D deficiency was much higher in the diabetes group than in the control group, and insufficiency was also more common.
When researchers looked at different subgroups of children with diabetes—separated by age, sex, where they lived, and other factors—the pattern held true: all these subgroups had lower vitamin D levels than their corresponding healthy peers.
Several factors influenced vitamin D levels in children with diabetes. Older children tended to have lower vitamin D levels than younger children. Children tested in winter and spring had lower levels than those tested in summer and fall, which makes sense because sunlight helps the body make vitamin D. Children who had recently been diagnosed with diabetes had different vitamin D levels than those who’d had it longer. Children with complications like diabetic ketoacidosis (a serious condition) also showed different patterns.
The study found that boys and girls had different vitamin D levels, though the exact pattern varied depending on age. Children living in urban areas had different vitamin D levels than those in rural areas. Blood sugar control (measured by HbA1C levels) was connected to vitamin D levels—children with better or worse control showed different vitamin D patterns. The season when children were admitted to the hospital significantly affected their vitamin D levels, with winter admissions showing lower levels.
Previous research has suggested that vitamin D deficiency might be more common in children with type 1 diabetes, and this study confirms that finding in a large Chinese population. The connection between vitamin D and immune system function is well-established, and since type 1 diabetes involves immune system problems, the link makes biological sense. However, this study adds new information about which specific factors (age, season, disease duration) most strongly affect vitamin D levels in these children.
The researchers were honest about their study’s limitations. Because they looked backward at existing medical records rather than following children forward in time, they couldn’t control for all the factors that might affect vitamin D levels. Important information was sometimes missing from the records. The study shows that vitamin D deficiency and type 1 diabetes are connected, but it cannot prove that low vitamin D causes diabetes or that treating vitamin D deficiency will prevent or improve diabetes. The researchers called for future studies that carefully collect all necessary information from the start to better understand this relationship.
The Bottom Line
Children with type 1 diabetes should have their vitamin D levels checked as part of routine care (moderate confidence). If deficiency or insufficiency is found, supplementation or increased dietary vitamin D intake may be appropriate—discuss with your child’s doctor (moderate confidence). Ensuring adequate sun exposure and vitamin D-rich foods is reasonable for all children, especially those with diabetes (moderate-to-high confidence).
Parents of children with type 1 diabetes should be aware of this connection and discuss vitamin D screening with their child’s endocrinologist. Healthcare providers treating children with type 1 diabetes should consider vitamin D status as part of comprehensive care. Children with type 1 diabetes who live in areas with limited sunlight or have dietary restrictions may benefit most from attention to vitamin D levels.
Vitamin D deficiency takes time to develop and time to correct. If a child is found to be deficient and starts supplementation, it typically takes 8-12 weeks to see meaningful improvements in blood vitamin D levels. Benefits to overall health and diabetes management would likely take longer to assess.
Frequently Asked Questions
Do children with type 1 diabetes have lower vitamin D levels?
Yes. A 2026 study of over 1,000 children found that those with type 1 diabetes had significantly lower vitamin D levels and much higher rates of deficiency compared to healthy children. Multiple factors including age, season, and disease duration influenced these levels.
What factors affect vitamin D levels in children with diabetes?
Age, season of testing, how long the child has had diabetes, sex, where they live, and blood sugar control all significantly influence vitamin D levels. Children tested in winter had lower levels than those tested in summer.
Does low vitamin D cause type 1 diabetes in children?
This study shows a connection between low vitamin D and type 1 diabetes, but cannot prove vitamin D deficiency causes diabetes. Researchers say more research is needed to understand whether treating vitamin D deficiency helps prevent or manage type 1 diabetes.
Should my child with type 1 diabetes take vitamin D supplements?
Discuss vitamin D screening and supplementation with your child’s endocrinologist. If testing shows deficiency or insufficiency, your doctor may recommend supplements or dietary changes. This should be part of comprehensive diabetes care.
How often should vitamin D be checked in children with type 1 diabetes?
The study doesn’t specify ideal screening frequency, but twice-yearly testing (spring and fall) would capture seasonal variations. Discuss appropriate screening schedules with your child’s healthcare provider based on their individual situation.
Want to Apply This Research?
- Track your child’s vitamin D supplementation (if prescribed) daily and log seasonal changes in outdoor activity time. Record vitamin D blood test results when available, noting the date and level.
- Set reminders for daily vitamin D supplementation if prescribed. Increase outdoor time during sunny months, especially in morning and afternoon. Add vitamin D-rich foods to meals (fortified milk, fatty fish, egg yolks) and track intake weekly.
- Schedule vitamin D blood tests twice yearly (spring and fall) to track seasonal patterns. Monitor adherence to supplementation through the app. Log any changes in diabetes control or symptoms that might correlate with vitamin D status. Share results with your child’s diabetes care team.
This article summarizes research findings and should not be considered medical advice. Vitamin D levels and supplementation decisions should be made in consultation with your child’s healthcare provider or endocrinologist. This study shows an association between vitamin D and type 1 diabetes but does not prove cause-and-effect. Do not start, stop, or change any diabetes medications or supplements without medical guidance. If your child has type 1 diabetes, work with their healthcare team to develop an appropriate care plan that may include vitamin D screening and management.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.