Tag: Type 2 diabetes

Considering Sex Hormones Led to Better Identification of Genes Linked to Type 2 Diabetes

Genomic and hormone study of white Europeans finds 22 additional disease-related variants

Ball and stick 3D model of testosterone. Source: Wikimedia CC0

Researchers identified almost two dozen previously unknown genetic variants linked to type 2 diabetes by including participants’ hormone levels in their analysis. Yan V. Sun of Emory University, USA, and colleagues reports these findings in the open-access journal PLOS Genetics.

Type 2 diabetes affects an increasing number of people worldwide, and more often affects men than women. The disease is caused by a mix of genetic and lifestyle factors, but little is known about how someone’s environment – both inside and outside the body – interacts with their genes to impact a person’s risk of developing the disease.

In the new study, researchers performed genome-wide interaction studies to investigate whether a person’s hormone levels interact with their genetic variants to affect their risk of developing type 2 diabetes. They grouped males and females independently and considered measurements of three types of sex hormones – total testosterone, bioavailable testosterone and sex-hormone binding globulin. The information came from white European participants in the UK Biobank, which contains biological samples and health data from half a million people.

The researchers used statistical analyses to identify relevant variants in the genomes of individuals with and without type 2 diabetes. By taking into account hormone levels, the analysis was able to identify 22 spots on the genome that increased a person’s risk for type 2 diabetes. These variants had not been reported previously in the most recent genomic study for type 2 diabetes.

The new study suggests that a person’s hormone levels may be interacting with their genes to increase their odds of having type 2 diabetes. For future studies, the researchers recommended that additional hormone measurements for each participant and more diverse cohorts should be included. They conclude that this approach, which includes environmental factors in genomic studies, may help us to identify additional disease-related genes and gain a better understanding of the mechanisms behind complex diseases.

The authors add, “We found that sex hormone levels contribute to differences in genetic risk factors for type 2 diabetes in men and women. By analyzing data for men and women separately, we identified new genetic associations with type 2 diabetes.”

The lead analyst, Amonae Dabbs-Brown notes, “I actually used to work at the CDC developing methods to measure some of these sex hormones. It’s really exciting to see what happens downstream. Maybe one day I’ll even get to see how these analyses are used in the clinic!”

Provided by PLOS

In your coverage, please use this URL to provide access to the freely available paper in PLOS Geneticshttps://plos.io/3ViXDKH

Contact: Rob Spahr [rob.spahr@emory.edu]

Citation: Dabbs-Brown A, Liu C, Hui Q, Wilson PW, Zhou JJ, Gwinn M, et al. (2025) Identification of gene-sex hormone interactions associated with type 2 diabetes among men and women. PLoS Genet 21(9): e1011470. https://doi.org/10.1371/journal.pgen.1011470

Author countries: United States

Funding: This work is supported in part by funding from the National Institutes of Health (HL154996 to YVS, DK139632 to YVS, and HL156991 to YVS). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. YVS received salary support from the National Institutes of Health.

Competing interests: The authors have declared that no competing interests exist.

Unmasking a New Diabetes Subtype in Sub-Saharan Africa

Photo by Wes Dissy on Unsplash

In this month’s podcast, QuickNews looks at a new Lancet study, “Non-autoimmune, insulin-deficient diabetes in children and young adults in Africa.” In this study, researchers report that a significant subset of what has previously been classified as Type 1 diabetes in sub-Saharan Africa may in fact be a distinct, novel form of the disease.

The individuals in this subset did not exhibit the typical autoimmune markers (islet autoantibodies) usually found in classic Type 1 diabetes in other parts of the world. The researchers instead identified a novel, non-autoimmune, insulin-deficient subtype of diabetes that is also distinct from Type 2 diabetes.

Further evidence of this new subtype was found in Black individuals in the USA, albeit less frequently, but not in White individuals. The discovery throws a spotlight on the heterogeneity of diabetes diagnoses in sub-Saharan Africa, and points to the need to consider alternative causes and explore new prevention and treatment strategies for this distinct form of the disease.

Hibernation ‘Superpowers’ May Be Hidden in Human DNA

Photo by Sangharsh Lohakare on Unsplash

Animals that hibernate are incredibly resilient. They can spend months without food or water, muscles refusing to atrophy, body temperature dropping to near freezing as their metabolism and brain activity slow to a crawl. When they emerge from hibernation, they recover from dangerous health changes similar to those seen in type 2 diabetes, Alzheimer’s disease, and stroke.

New genetic research suggests that hibernating animals’ superpowers could lie hidden in human DNA – with clues on how to unlock them, perhaps one day leading to treatments that could reverse neurodegeneration and diabetes.

Two studies describing the results are published in Science.

The genetics of metabolism and obesity

A gene cluster called the “fat mass and obesity (FTO) locus” plays an important role in hibernators’ abilities, the researchers found. Intriguingly, humans have these genes too. “What’s striking about this region is that it is the strongest genetic risk factor for human obesity,” says Chris Gregg, PhD, professor in neurobiology and human genetics at University of Utah Health and senior author on the studies. But hibernators seem able to use genes in the FTO locus in new ways to their advantage.

The team identified hibernator-specific DNA regions that are near the FTO locus and that regulate the activity of neighbouring genes, tuning them up or down. The researchers speculate that adjusting the activity of neighbouring genes, including those in or near the FTO locus, allows hibernators to pack on the pounds before settling in for the winter, then slowly use their fat reserves for energy throughout hibernation.
 
Indeed, the hibernator-specific regulatory regions outside of the FTO locus seem crucial for tweaking metabolism. When the researchers mutated those hibernator-specific regions in mice, they saw changes in the mice’s weight and metabolism. Some mutations sped up or slowed down weight gain under specific dietary conditions; others affected the ability to recover body temperature after a hibernation-like state or tuned overall metabolic rate up or down. 

Intriguingly, the hibernator-specific DNA regions the researchers identified weren’t genes themselves. Instead, the regions were DNA sequences that contact nearby genes and turn their expression up or down, like an orchestra conductor fine-tuning the volume of many musicians. This means that mutating a single hibernator-specific region has wide-ranging effects extending far beyond the FTO locus, explains Susan Steinwand, research scientist in neurobiology at U of U Health and first author on one of the studies.  “When you knock out one of these elements – this one tiny, seemingly insignificant DNA region – the activity of hundreds of genes changes,” she says. “It’s pretty amazing.”
 
Understanding hibernators’ metabolic flexibility could lead to better treatments for human metabolic disorders like type 2 diabetes, the researchers say. “If we could regulate our genes a bit more like hibernators, maybe we could overcome type 2 diabetes the same way that a hibernator returns from hibernation back to a normal metabolic state,” says Elliott Ferris, MS, bioinformatician at U of U Health and first author on the other study.

Uncovering the regulation of hibernation

Finding the genetic regions that may enable hibernation is a problem akin to excavating needles from a massive DNA haystack. To narrow down the regions involved, the researchers used multiple independent whole-genome technologies to ask which regions might be relevant for hibernation. Then, they started looking for overlap between the results from each technique.

First, they looked for sequences of DNA that most mammals share but that had recently changed in hibernators. “If a region doesn’t change much from species to species for over 100 million years but then changes rapidly and dramatically in two hibernating mammals, then we think it points us to something that is important for hibernation, specifically,” Ferris says.

To understand the biological processes that underlie hibernation, the researchers tested for and identified genes that turn up or down during fasting in mice, which triggers metabolic changes similar to hibernation. Next, they found the genes that act as central coordinators, or “hubs,” of these fasting-induced changes to gene activity.

Many of the DNA regions that had recently changed in hibernators also appeared to interact with these central coordinating hub genes. Because of this, the researchers expect that the evolution of hibernation requires specific changes to the controls of the hub genes. These controls comprise a shortlist of DNA elements that are avenues for future investigation.

Awakening human potential

Most of the hibernator-associated changes in the genome appeared to “break” the function of specific pieces of DNA, rather than confer a new function. This hints that hibernators may have lost constraints that would otherwise prevent extreme flexibility in the ability to control metabolism. In other words, it’s possible that the human “thermostat” is locked to a narrow range of continuous energy consumption. For hibernators, that lock may be gone.

Hibernators can reverse neurodegeneration, avoid muscle atrophy, stay healthy despite massive weight fluctuations, and show improved aging and longevity. The researchers think their findings show that humans may already have the needed genetic code to have similar hibernator-like superpowers—if we can bypass some of our metabolic switches. 

“Humans already have the genetic framework,” Steinwand says. “We just need to identify the control switches for these hibernator traits.” By learning how, researchers could help confer similar resilience to humans.

Source: University of Utah Health

Study Finds Higher Cardiovascular Risk for One Particular Sulfonylurea

Photo by Stephen Foster on Unsplash

New research from investigators at Mass General Brigham suggests that a commonly used type 2 diabetes medication is linked to a higher rate of heart-related conditions compared to medications that hit other targets. The study examined nationwide data from nearly 50,000 patients treated with different sulfonylureas and found that glipizide – the most widely used drug in the US within this category, but not available in South Africa – was linked to higher incidence of heart failure, related hospitalisation and death compared to dipeptidyl peptidase-4 (DPP-4) inhibitors. Results are published in JAMA Network Open.

“Patients with type 2 diabetes are at heightened risk of adverse cardiovascular incidents such as stroke and cardiac arrest,” said corresponding author Alexander Turchin, MD, MS, of the Division of Endocrinology at Brigham and Women’s Hospital (BWH), a founding member of the Mass General Brigham healthcare system. “While sulfonylureas are popular and affordable diabetes medications, there is a lack of long-term clinical data on how they affect cardiac health in comparison to more neutral alternatives like dipeptidyl peptidase 4 inhibitors.”

Turchin and co-authors emulated a target trial by analysing electronic health records and insurance claims data from the BESTMED consortium. The cohort included 48 165 patients with type 2 diabetes and moderate cardiovascular risk who received care at 10 different study sites across the country, including BWH, as well as those covered by two different national health insurance plans.

The researchers studied the five-year risk of major adverse cardiovascular events in patients treated with different sulfonylureas (glimepiride, glipizide or glyburide) or DPP4i in addition to metformin, a primary diabetes medication. They found that glipizide was associated with a 13% increase in cardiovascular risk when compared to DPP4i, while glimepiride and glyburide led to relatively smaller and less clear effects, respectively. The authors propose that further research is needed to uncover the underlying mechanisms.

“Our study underscores the importance of evaluating each drug in a particular pharmacological class on its own merits,” said Turchin. 

Source: Mass General Brigham

Intermittent Energy Restriction May Improve Outcomes in People with Obesity and Type 2 Diabetes

Photo by I Yunmai on Unsplash

Intermittent energy restriction, time-restricted eating and continuous energy restriction can all improve blood sugar levels and body weight in people with obesity and type 2 diabetes, according to a study being presented Sunday at ENDO 2025, the Endocrine Society’s annual meeting in San Francisco, Calif.

“This study is the first to compare the effects of three different dietary interventions intermittent energy restriction (IER), time-restricted eating (TRE) and continuous energy restriction (CER) in managing type 2 diabetes with obesity,” said Haohao Zhang, PhD, chief physician at The First Affiliated Hospital of Zhengzhou University in Zhengzhou, China.

Although researchers identified improved HbA1c levels, and adverse events were similar across the three groups, the IER group showed greater advantages in reducing fasting blood glucose, improving insulin sensitivity, lowering triglycerides, and strengthening adherence to the dietary interventions.

“The research fills a gap in directly comparing 5:2 intermittent energy restriction with a 10-hour time-restricted eating in patients with obesity and type 2 diabetes. The findings provide scientific evidence for clinicians to choose appropriate dietary strategies when treating such patients,” Zhang says.

Zhang and colleagues performed a single-centre, randomised, parallel-controlled trial at the First Affiliated Hospital of Zhengzhou University from November 19, 2021 to November 7, 2024.

Ninety patients were randomly assigned in a 1:1:1 ratio to the IER, TRE or CER group, with consistent weekly caloric intake across all groups. A team of nutritionists supervised the 16-week intervention.

Of those enrolled, 63 completed the study. There were 18 females and 45 males, with an average age of 36.8 years, a mean diabetes duration of 1.5 years, a baseline BMI of 31.7kg/m², and an HbA1c of 7.42%.

At the end of the study, there were no significant differences in HbA1c reduction and weight loss between the IER, TRE and CER groups. However, the absolute decrease in HbA1c and body weight was greatest in the IER group.

Compared to TRE and CER, IER significantly reduced fasting blood glucose and triglycerides and increased the Matsuda index, a measure of whole-body insulin sensitivity. Uric acid and liver enzyme levels exhibited no statistically significant changes from baseline in any study group.

Two patients in the IER group and the TRE group, and three patients in the CER group, experienced mild hypoglycemia.

The IER group had the highest adherence rate (85%), followed by the CER group at 84% and the TRE group at 78%. Both the IER and CER groups showed statistically significant differences compared with the TRE group.

Zhang said these findings highlight the feasibility and effectiveness of dietary interventions for people who have obesity and type 2 diabetes.

Source: The Endocrine Society

Could the Brain be Targeted to Treat Type 2 Diabetes?

Source: CC0

Successfully treating type 2 diabetes may involve focusing on brain neurons, rather than simply concentrating on obesity or insulin resistance, according to a study published in the Journal of Clinical Investigation.  

For several years, researchers have known that hyperactivity of a subset of neurons located in the hypothalamus, called AgRP neurons, is common in mice with diabetes. 

“These neurons are playing an outsized role in hyperglycaemia and type 2 diabetes,” said UW Medicine endocrinologist Dr Michael Schwartz, corresponding author of the paper.

To determine if these neurons contribute to elevated blood sugar in diabetic mice, researchers employed a widely used viral genetics approach to make AgRP neurons express tetanus toxin, which prevents the neurons from communicating with other neurons. 

Unexpectedly, this intervention normalised high blood sugar for months, despite having no effect on body weight or food consumption.   

Conventional wisdom is that diabetes, particularly type 2 diabetes, stems from a combination of genetic predisposition and lifestyle factors, including obesity, lack of physical activity and poor diet. This mix of factors leads to insulin resistance or insufficient insulin production.  

Until now, scientists have traditionally thought the brain doesn’t play a role in type 2 diabetes, according to Schwartz. 

The paper challenges this and is a “departure from the conventional wisdom of what causes diabetes,” he said. 

The new findings align with studies published by the same scientists showing that injection of a peptide called FGF1 directly into the brain also causes diabetes remission in mice. This effect was subsequently shown to involve sustained inhibition of AgRP neurons.

Together, the data suggest that, while these neurons are important for controlling blood sugar in diabetes, they don’t play a major role in causing obesity in these mice, the researchers noted in their report.  

In other words, targeting these neurons may not reverse obesity, even as it causes diabetes to go into remission, Schwartz explained. 

More research is needed on how to regulate activity in these neurons, and how they become hyperactive in the first place, he said. Once these questions are answered, Schwartz said that a therapeutic approach might then be developed to calm them down. 

This approach could represent a shift in how clinicians understand and treat this chronic disease, Schwartz said.  He noted, for instance, that semaglutide and other new drugs used to treat type 2 diabetes are also able to inhibit AgRP neurons.  

The extent to which this effect contributes to the antidiabetic action of these drugs is unknown. Further research might help scientists to better understand the role of AgRP neurons in how the body normally controls blood sugar, and to ultimately translate these findings into human clinical trials, he added.  

Source: University of Washington School of Medicine/UW Medicine

Simpler Blood Glucose Monitoring to Delay or Prevent Onset of Diabetes

Photo by Photomix Company on Pexels

The highs and lows of blood glucose aren’t just an energy rollercoaster; they could be a key to detecting diabetes risk early and spare a needle prick or two.

Researchers at the University of Tokyo have identified a simple, noninvasive method for assessing blood glucose regulation – an essential factor in diabetes risk. Their approach, based on continuous glucose monitoring (CGM) data, could improve early detection and risk assessment for diabetes without relying on blood samples and expensive or complex procedures.

The study is published in Communications Medicine.

Often called a “silent epidemic,” diabetes is an increasingly prevalent global health concern, with significant health and economic consequences. Early detection of impaired glucose regulation – an intermediate stage between normal blood glucose levels and diabetes – is essential for preventing or delaying the onset of Type 2 diabetes. Conventional diagnostic tools, however, often miss early signs because they rely on periodic blood samples rather than continuous monitoring.

“Traditional diabetes tests, while useful, do not capture the dynamic nature of glucose regulation under physiological conditions,” said Shinya Kuroda, a professor at the University of Tokyo’s Graduate School of Science and co-author of the current study.

To find a more practical alternative, the team turned to CGM, a wearable technology that continuously tracks glucose levels in real time, providing a clearer picture of blood glucose fluctuations in everyday life. Their goal was to identify a CGM-based method for estimating glucose handling capacity, which maintains stable levels, without invasive procedures.

The team analyzed 64 individuals without a prior diabetes diagnosis, using a CGM device, oral glucose tolerance tests (OGTT), and clamp tests that are used to assess insulin sensitivity and glucose metabolism. They then validated their findings with an independent dataset and mathematical simulations.

Their analysis showed that AC_Var, a measure of glucose-level fluctuations, strongly correlates with the disposition index, a well-established predictor of future diabetes risk. Moreover, the researchers’ model, which combines AC_Var with glucose standard deviation, outperformed traditional diabetes markers – such as fasting blood glucose, HbA1c and OGTT results – in predicting the disposition index.

“By analysing CGM data with our new algorithm, we identified individuals with impaired glycaemic control – even when standard diagnostic tests classified them as ‘normal,’” said Kuroda. “This means we can potentially detect issues much earlier, creating an opportunity for preventive interventions before diabetes is diagnosed.”

The team also showed that the method was more accurate than conventional diagnostic indicators in predicting diabetes complications such as coronary artery disease. To facilitate broader access to this approach, the research team has developed a web application that allows individuals and health care providers to easily calculate these CGM-based indices.

“Our ultimate goal is to provide a practical, accessible tool for widespread diabetes screening,” Kuroda said. “By enabling early detection of glucose regulation abnormalities, we hope to prevent or delay disease onset and reduce long-term complications.”

Source: University of Tokyo

High Muscle Strength Linked to Lower Risk of Type 2 Diabetes

Photo by Jonathan Borba on Unsplash

Researchers from the School of Public Health, LKS Faculty of Medicine of the University of Hong Kong (HKUMed) conducted a large-scale epidemiological study to explore the potential health benefits of high muscle strength in preventing type 2 diabetes (T2D) across varying levels of genetic risk. The study found that higher muscle strength was associated with over 40% lower risk of T2D, regardless of genetic susceptibility to T2D. The study highlights the importance of maintaining or improving muscle strength as a key strategy for preventing T2D. The findings were published in BMC Medicine.

T2D is one of the most common chronic metabolic disorders, and it is associated with an increased risk of various complications, including heart disease, stroke, high blood pressure, and narrowing of blood vessels. It is characterised by hyperglycaemia, due to insulin resistance and impaired insulin secretion. Evidence suggests that around 10% of the global population is affected by T2D, therefore, preventing T2D is a significant global public health concern. T2D can be caused by the interplay between non-modifiable genetic traits and modifiable lifestyle factors. Muscle strength is an important aspect of muscular fitness, and it has been found to be associated with lower risk of various cardiometabolic diseases including T2D. However, it remains unclear whether improving muscle strength should be considered a T2D prevention strategy in individuals with varying levels of genetic susceptibility to T2D, particularly those with high genetic susceptibility to T2D.

The research utilised data of 141 848 white British individuals without baseline T2D from the UK Biobank, an ongoing prospective cohort of over 500 000 UK adults which includes extensive genotype and phenotype information. Muscle strength was assessed in the form of grip strength. Genetic risk of T2D was estimated based on 138 known genetic variants for T2D.

The participants were followed up for more than seven years. During the follow-up period, 4,743 new T2D cases were identified. The findings indicated that, compared with low muscle strength, individuals with high muscle strength was associated with a 44% lower relative risk of developing T2D, even after taking into account T2D genetic risk as well as other risk factors. Moreover, the research team observed evidence of an interaction between muscle strength and genetic susceptibility to T2D, suggesting that muscle strength may play a role in modifying the impact of genetic risk to T2D onset. The findings further revealed that individuals at high genetic risk of T2D but with high muscle strength could have a lower absolute risk of T2D, compared with those at low or medium genetic risk but with low muscle strength.

This groundbreaking study uncovered the first-ever prospective associations between muscle strength, genetic susceptibility to type 2 diabetes, and the risk of developing the disease. ‘The findings emphasise the crucial role of maintaining or enhancing muscle strength as a key strategy for preventing T2D in middle-aged and older adults, regardless of their genetic risk levels and including those at high genetic risk. We believe that these results offer novel insights into the significant impact of higher muscle strength on metabolic health,’ said Dr Wang Mengyao, from the School of Public Health at HKUMed, the first author of this study.

‘This study highlights the significance of Biobank studies in examining the interaction between exposures and genetics in influencing the risk of T2D. Further research utilising ethnic-specific Biobank studies is needed to determine if these findings are applicable to other populations, such as East Asians,’ expressed Professor Ryan Au Yeung, Assistant Professor from the School of Public Health at HKUMed, a co-author of this study.

‘Individuals in middle-to-late life are at increased risk of type 2 diabetes. However, our study has demonstrated the potential roles of high muscle strength in preventing the future risk of developing type 2 diabetes not only in all individuals, but also in individuals with high genetic predisposition to type 2 diabetes. Our study supports the current public health guidelines which suggest that adults should engage in muscle-strengthening activities for at least two days per week from a disease prevention perspective,’ added Professor Youngwon Kim, from the School of Public Health at HKUMed, the corresponding author of the study.

Source: The University of Hong Kong

Millions of Diabetes and Heart Disease Cases Linked to Sugary Drinks, New Study Finds

Photo by Breakingpic on Pexels

A new study from researchers at Tufts University, which appears in Nature Medicine, estimates that 2.2 million new cases of type 2 diabetes and 1.2 million new cases of cardiovascular disease occur each year globally due to consumption of sugar-sweetened beverages.

In developing countries, the case count is particularly sobering. In Sub-Saharan Africa, the study found that sugar-sweetened beverages contributed to more than 21% of all new diabetes cases. In Latin America and the Caribbean, they contributed to nearly 24% of new diabetes cases and more than 11% of new cases of cardiovascular disease.

Colombia, Mexico, and South Africa are countries that have been particularly hard hit.  More than 48% of all new diabetes cases in Colombia were attributable to consumption of sugary drinks. Nearly one third of all new diabetes cases in Mexico were linked to sugary drink consumption. In South Africa, 27.6% of new diabetes cases and 14.6% of cardiovascular disease cases were attributable to sugary drink consumption.

Sugary beverages are rapidly digested, causing a spike in blood sugar levels with little nutritional value. Regular consumption over time leads to weight gain, insulin resistance, and a host of metabolic issues tied to type 2 diabetes and heart disease, two of the world’s leading causes of death.

“Sugar-sweetened beverages are heavily marketed and sold in low- and middle-income nations. Not only are these communities consuming harmful products, but they are also often less well equipped to deal with the long-term health consequences,” says Dariush Mozaffarian, senior author on the paper and director of the Food is Medicine Institute at the Friedman School.

As countries develop and incomes rise, sugary drinks become more accessible and desirable, the authors say. Men are more likely than women to suffer the consequences of sugary drink consumption, as are younger adults compared to their older counterparts, the researchers say.

“We need urgent, evidence-based interventions to curb consumption of sugar-sweetened beverages globally, before even more lives are shortened by their effects on diabetes and heart disease,” says Laura Lara-Castor, NG24, first author on the paper who earned her PhD at the Friedman School and is now at the University of Washington.

The study’s authors call for a multi-pronged approach, including public health campaigns, regulation of sugary drink advertising, and taxes on sugar-sweetened beverages.  Some countries have already taken steps in this direction. Mexico, which has one of the highest per capita rates of sugary drink consumption in the world, introduced a tax on the beverages in 2014. Early evidence suggests that the tax has been effective in reducing consumption, particularly among lower-income individuals. 

“Much more needs to be done, especially in countries in Latin America and Africa where consumption is high and the health consequence severe,” says Mozaffarian. “As a species, we need to address sugar-sweetened beverage consumption.”

Source: Tufts University

Five Years of Vitamin D Supplements Fails to Prevent Diabetes

Photo by Michele Blackwell on Unsplash

Using significantly higher doses of vitamin D than recommended for five years did not affect the incidence of type 2 diabetes in elderly men and women, according to a new study from the University of Eastern Finland which appears in Diabetologia.

In population studies, low levels of vitamin D in the body have been associated with a higher risk of type 2 diabetes, but such observational studies cannot directly prove a causative link. Experimental studies have shown that the use of significantly higher doses of vitamin D than recommended slightly reduces the risk of developing type 2 diabetes in individuals with impaired glucose metabolism, ie, those with prediabetes. In contrast, no effects have been observed in individuals without prediabetes. However, the studies with non-prediabetic subjects have used relatively small doses of vitamin D or have been short-term. Until now, there has been no research data on the effects of long-term use of high doses of vitamin D on the risk of type 2 diabetes in individuals without glucose metabolism disorders.

In the Finnish Vitamin D Trial (FIND) conducted at the University of Eastern Finland from 2012 to 2018, 2 495 men aged 60 and older and women aged 65 and older were randomised for five years into either a placebo group or groups receiving either 40 or 80 micrograms of vitamin D3 per day. In the statistical analyses of the now-published sub-study, 224 participants who were already using diabetes medications at the start of the study were excluded. Comprehensive information was collected from the participants on lifestyle, nutrition, diseases, and their risk factors. Data was also obtained from national health registers. About one-fifth were randomly selected for more detailed examinations, and blood samples were taken from them.

During the five years, 105 participants developed type 2 diabetes: 38 in the placebo group, 31 in the group receiving 40 micrograms of vitamin D3 per day, and 36 in the group receiving 80 micrograms of vitamin D3 per day. There was no statistically significant difference in the number of cases between the groups.

In the more closely studied group of 505 participants, the blood calcidiol level, which describes the body’s vitamin D status, was on average 75nmol/L at the start, and only 9% had a low level, ie, below 50nmol/L. After one year, the calcidiol level was on average 100nmol/L in the group that used 40 micrograms of vitamin D per day and 120nmol/L in the group that used 80 micrograms of vitamin D per day. There was no significant change in the placebo group. The effects of vitamin D on blood glucose and insulin levels, body mass index, and waist circumference were examined during the first two years of the study, but no differences were observed between the groups.

The findings of the FIND study reinforce the view that the use of higher doses of vitamin D than recommended does not significantly affect the risk of developing type 2 diabetes in individuals without prediabetes and who already have a good vitamin D status. So far, there is no research data on whether high doses of vitamin D can be beneficial in preventing type 2 diabetes in individuals without prediabetes but with vitamin D deficiency.

Source: University of Eastern Finland