Vitamin D deficiency just a "bone thing"? The Lancet tells you: diabetes "has a share"!

Of the 5272 TILDA participants included, 4612 (87.
5%) had normal blood glucose levels, 242 (4.
6%) were prediabetic, and 418 (7.
9%) had diabetes
.
Participants with normal blood glucose (58 nmol/L) had the highest vitamin D concentrations compared to participants with prediabetes (53.
8 nmol/L) and diabetes (49.
8 nmol/L) (p<0.
0001).

。

Adjusted and unadjusted logistic regression models (n = 5272) for assessing vitamin D levels for epidemic and recurrent diabetes showed an association between vitamin D concentration (nmol/L) and diabetes probability, relative hazard ratio (RRR) is 0.
99 (p = 0.
005).

Compared with vitamin D≥75 nmol/L, vitamin levels ranged from 30~<50 nmol/L (RRR 1.
62; 95% CI: 1.
17, 2.
24; p = 0.
004) and <30 nmol/L (RRR 1.
50; 95% CI: 1.
03, 2.
18; p = 0.
037).
of participants were more
likely to develop type 2 diabetes.

The researchers also found that 3409 of the 5272 TILDA participants had normal blood sugar levels, 157 were prediabetic, and 262 had diabetes.
Of the other 3,828 TILDA participants, 2,992 had normal blood sugar, 499 were prediabetic, and 337 had diabetes
.

A Logistic regression model assessing diabetes status after 4 years showed that when vitamin D < 30 nmol/L, the likelihood of developing prediabetes was increased by 62% (RRR: 1.
62, 95% CI: 1.
12, 2.
35; p = 0.
011).

At the same time, participants were also observed to progress from prediabetes to diabetes in 32.
5%.

The findings suggest that higher concentrations of vitamin D levels are associated
with a reduced risk of diabetes.
Compared with participants < 50 nmol/L, the likelihood of developing prediabetes at a concentration of ≥75 nmol/L was reduced by more than a third; At concentrations of 30 to 50 nmol/L, the likelihood of developing prediabetes was not significantly reduced
.
However, this concentration was associated with a 42% increase in the likelihood of developing prediabetes compared to having adequate levels*, suggesting that the benefit from higher vitamin D concentrations became significant from 50 nmol/L, which is also adequate from
a bone health perspective.

*Note: According to the guidelines of the Institute of Medicine (IOM), vitamin D concentrations < 30 nmol/L (deficiency), 30~<50 nmol/L (insufficient) and ≥50 nmol/L (sufficient).

It is therefore reasonable to conclude that improving vitamin D levels may significantly reduce or at least delay the progression to
diabetes.

Expert interviews

Medical profession

What do you think of the results of this study?

Text version of the answer:

In recent years, the relationship between vitamin D and the development of diabetes has attracted much attention, and previous prospective studies of DPVD have suggested that vitamin D treatment can significantly prevent the development of type 2 diabetes in pre-diabetic people, and population studies have also suggested that vitamin D can reduce immune-mediated damage to related islets β cells in T1DM patients
.
But the relationship between the two has been controversial, and this study adds new evidence
to clarify the relationship.

At the same time, vitamin D insufficiency or deficiency is still common in the population, and can even be considered a serious but not taken seriously "epidemic", and the results of this study not only arouse people's attention to vitamin D supplementation therapy, but also have great significance
for diabetes prevention and treatment.

Secondly, as mentioned in the study, the occurrence and development of diabetes usually takes more than 10 years to appear, and the results of WhiteHall II also show that it generally takes 13 years from normal blood glucose to impaired glucose tolerance to the emergence of diabetes, and the study observed a significant effect relationship between vitamin D levels and the development of prediabetes during the 4-year follow-up period, making the results more meaningful
.

This suggests that vitamin D deficiency or insufficiency may accelerate the onset and progression
of diabetes.
Although the study also suggested that after correction, vitamin D deficiency, deficiency and adequacy did not affect the incidence of
diabetes.
However, extending the follow-up period may further reveal a significant association
between diabetes risk and vitamin D levels.

Medical profession

What are the clinical implications of this study for the prevention and treatment of clinical diabetes and vitamin D deficiency?

Text version of the answer:

A new discussion of vitamin D supplementation was added to the 2022 American Diabetes Association (ADA) guidelines, which stated: "Although prospective randomized controlled trials of vitamin D and type 2 diabetes have not observed significant benefits of vitamin D supplementation in people at high risk of type 2 diabetes; But post-hoc and meta-analyses suggest potential benefits
for specific populations.
Further research is needed to determine patient characteristics and clinical indicators
of possible benefit from vitamin D supplementation.
"This study provides new strong evidence in this regard, which discusses the risks associated with developing prediabetes in people with vitamin D deficiency, insufficiency and adequacy, and provides appropriate clinical intervention cut-off points, providing valuable guidance for
diabetes prevention and treatment in this population.
"

At the same time, this longitudinal observation study takes prediabetes as one of the endpoint events to be observed, which is also of positive significance
for the prevention and treatment of diabetes in people with normal blood glucose levels.
If it is widely applied to early intervention in specific populations, it will have a significant impact on
the prevention of diabetes at the population level and delay the onset and progression of diabetes.

Medical profession

Based on the study's conclusions, can the public "unscrupulously" supplement with vitamin D? How to supplement properly?

Text version of the answer:

There is no consensus on
how much vitamin D supplementation provides the best clinical results.
However, vitamin D is a fat-soluble vitamin, and excessive doses can accumulate in the body and cause drug poisoning
.

Vitamin D poisoning is mostly manifested as non-specific symptoms, such as anorexia, diarrhea, exhaustion, frequent urination, itching, etc.
, long-term chronic poisoning can be due to persistent blood calcium rise, resulting in metastatic calcification
of blood vessels, kidneys and other organs.

According to the Guidelines for Vitamin D and Bone Health in Adults (2014 Simplified Edition), daily vitamin D supplementation of 10,000 IU < usually does not cause toxicity, and when the dose is ≥ 50,000 IU/day for weeks or months, it often leads to toxicity<b20>.

The safe upper limit of vitamin D intake for adults and children over 11 years of age is 4000 IU/day (100 micrograms/day), but the specific upper limit of vitamin D supplementation varies according to age and metabolic status, and the recommended daily dose of vitamin D for healthy adults is between
400 and 800 IU.