A high intake of vitamin D supplements may lower the risk of type 2 diabetes in adults with prediabetes by 15 per cent, an analysis published Tuesday in the medical journal, Annals of Internal Medicine, has found.
Researchers from Tufts Medical Center conducted a systematic review and meta-analysis of three clinical trials comparing the impact of vitamin D supplement on diabetes risk.
The authors found that over a 3 three-year follow-up period, diabetes occurred in 22.7 per cent of adults who received vitamin D and 25 per cent of those who received placebo, which is a 15 per cent relative reduction in risk.
Type 2 diabetes usually starts in midlife and often affects people who are overweight. Cells become less responsive to insulin – a hormone that regulates blood sugar levels– once a person suffers from this type of diabetes – cross check the information.
The individual participant data (IPD) meta-analysis combined primary data from the three vitamin D and diabetes prevention trials, which were specifically designed and conducted to test whether Vitamin D reduces risk of diabetes in adults with prediabetes: Tromsø (Norway), D2d (US) and DPVD (Japan).
The scientists looked for studies that included adults who took 4,000 International Units (IU) of Vitamin D supplements with a three-year follow-up. They ended up with 2,097 participants who took Vitamin D supplements and 2,093 who received a placebo.
All 4,190 participants from the three trials contributed data to the meta-analysis. Participants were randomly assigned to receive Vitamin D or placebo.
The mean age of participants was 61 years with 44% being women while 51% identified themselves as White or European, 33% as Asian, and 15% as Black.
In all three trials, the risk for diabetes was reduced in the group assigned to Vitamin D as compared to the placebo group.
After combining IPD, the study found that Vitamin D reduced the risk of progression from prediabetes to diabetes by 15 per cent. It also found that Vitamin D increased the likelihood of regression to normal glucose regulation by 30 per cent. There was no evidence of risk.
The researchers also pointed out that vitamin D supplements could be an inexpensive way to delay type 2 diabetes in more than 10 million people worldwide with prediabetes.
Vitamin D, which is a fat-soluble vitamin mostly found in sunlight, has multiple benefits for the body, including insulin secretion and glucose metabolism.
The study found that low levels of vitamin D in the blood increased the risk of developing diabetes. In adults with prediabetes, vitamin D is effective in decreasing the risk of the disease.
Remaining questions
The authors, through their meta-analysis, speculate that the optimal effect is possibly above the range of 125 to 150 nanomoles per litre”, whereas the adverse effects of Vitamin D therapy just above the upper limit are unknown.
Additionally, they noted that question remains if this very high dose causes hypercalcemia – a condition in which the calcium level in your blood is above normal – or hypercalciuria – a condition that has excess calcium in the urine.
And what is still unknown is whether this very high dose causes other harms, such as falls in older adults or other adverse effects.
The exclusions included children, pregnant or lactating women, hospitalised patients, those with end-stage renal disease, and HIV.
The studied population included people at high risk for type 2 diabetes, so the results do not apply to the general healthy population and should not be extrapolated to those who are at average risk for type 2, type 1, or other types of diabetes (such as monogenic diabetes), the research mentioned.
An editorial note authored by Malachi J. McKenna, and Mary A.T. Flynn, underlines that although Vitamin D may reduce diabetes risk in some people, high-dose Vitamin D therapy could cause harm.. They cautioned that its high intake can lead to kidney stones and other health problems, so people should only take such a course after consulting their doctor.
The researchers stress that professional societies, which advise physicians about benefits and harms of Vitamin D therapy, have “a duty of care” to understand advice from government agencies. And that they should promote population health recommendations about Vitamin D intake requirements and safe limits.
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