A recent analysis conducted by Swedish researchers, involving over 93,000 adults, has shed light on a common practice in Spain that significantly increases the risk of developing diabetes in the future. This alarming habit is now known to have a profound impact on metabolism.
Diabetes is a growing concern in Spain, with the Spanish Diabetes Society (SED) estimating that approximately 5.1 million adults in the country are living with this metabolic condition. This figure represents a staggering 42% increase since 2019.
Dr. Antonio Pérez Pérez, the president of the SED and the director of the Endocrinology and Nutrition Unit at the Hospital de la Santa Creu i Sant Pau in Barcelona, expresses deep concern over this trend. He states, "Over the last two years, we have witnessed a significant surge in the number of adults grappling with diabetes in Spain. This is a worrisome trend that impacts the lives of millions of people across the nation."
To put this into perspective, it's estimated that one in seven adults in Spain is affected by diabetes, making it the European country with the second-highest prevalence of the disease. It's important to note that these figures may actually underestimate the problem, as approximately 30.3% of individuals with diabetes in Spain remain undiagnosed.
The critical issue with undiagnosed or improperly managed diabetes is the potential for serious and even life-threatening complications, including heart attacks, strokes, kidney failure, vision loss, and limb amputation.
Various theories have been put forth to explain the surge in diabetes cases. Yuxia Wei, a professor at Sweden's esteemed Karolinska Research Institute, has led groundbreaking research on this topic. Her findings, presented at the European Association for the Study of Diabetes (EASD) conference, suggest a significant association between one prevalent and harmful habit in Europe and the development of type 2 diabetes.
That habit is smoking tobacco, which is unfortunately prevalent in more than a quarter of the Spanish population. Dr. Wei's research reveals that current smokers face a staggering 73% higher risk of developing type 2 diabetes compared to those who have never smoked. Notably, her study is the first to establish a "metabolic signature" capable of predicting which smokers are most susceptible to diabetes.
Wei elaborates on the significance of their findings: "Our study has pioneered the development of a metabolic signature for smoking based on comprehensive metabolomic profiles. It offers fresh insights into how smoking impacts metabolism, heightening the risk of type 2 diabetes."
The study's conclusion is rooted in the fact that smoking affects 131 metabolites, small compounds produced during metabolic processes, which circulate in the bloodstream and influence various aspects of health, including cholesterol levels.
While earlier observational studies indicated that smokers were 20% to 60% more likely to develop type 2 diabetes, the underlying mechanisms remained unclear. To bridge this gap, researchers scrutinised metabolites present in blood samples from a massive cohort of 93,722 individuals, sourced from the UK Biobank, a repository of genetic, health, and lifestyle data from half a million subjects.
Employing magnetic resonance spectroscopy (MRI), they identified the 131 metabolites that can effectively predict which smokers are at the highest risk of developing type 2 diabetes. These participants were both current and former smokers, aged 37 to 73, without diabetes at the study's outset in 2006. Over a median follow-up period of 13 years, 1,869 new cases of diabetes emerged.
Several of the metabolites affected by smoking are glycoproteins (inflammatory markers) and fatty acids, which collectively indicated an individual's likelihood of developing type 2 diabetes.
The study shows that 73% of the heightened risk associated with current smoking can be attributed to the smoking-related metabolic signature, even after accounting for traditional diabetes risk factors such as age, sex, education level, ethnicity, BMI, physical activity, diet, and family history of diabetes.
Smoking was also found to elevate unhealthy saturated and monounsaturated fatty acids while diminishing the presence of beneficial polyunsaturated fatty acids such as DHA, omega-6, and omega-3 fatty acids, which play protective roles in heart health and various bodily functions.
Furthermore, smoking was linked to metabolites associated with higher triglycerides and harmful LDL cholesterol, as well as reduced levels of all forms of HDL cholesterol, commonly referred to as "good cholesterol."
The silver lining from this research is the recognition that most smoking-induced metabolic changes are reversible following smoking cessation. Additionally, the analysis identified that a high level of the metabolic signature correlated with a 61% increased risk of developing type 2 diabetes compared to those with a low level of this signature.
Genetic factors also play a role, with individuals possessing both an elevated metabolic signature and a high genetic susceptibility to type 2 diabetes being three times more likely to develop the disease. This highlights the importance of people with a heightened genetic risk avoiding smoking even more vigorously than the general population.
The researchers validated their metabolic signature using blood samples from 3,626 participants in the TwinGene study, a cohort of Swedish individuals. Remarkably, the metabolic signature for predicting type 2 diabetes risk remained consistent, despite differences in dietary habits, lifestyles, and environmental exposures between the UK and Sweden.
Wei underscores the robustness of their findings, stating, "The reproducibility of the results in the Swedish population indicates the robustness of the method. However, more than half of the relationship between smoking and diabetes was not explained by metabolic signature, suggesting that other pathophysiological consequences of smoking play a role in the development of diabetes. These mechanisms could include the adverse effects of tobacco on pancreatic tissue and beta cell function."