A new ‘global atlas’ study characterizes insomnia as a novel risk factor for developing type 2 diabetes. In total, the researchers identified 19 risk factors and dismissed 21 suggestive risk factors based on insufficient scientific evidence.
Globally, around 463 million adults lived with diabetes in 2019, according to the International Diabetes Federation (IDF). In 2015, approximately 9% of all adults had the condition.
Diabetes is a condition where sugar or glucose builds up in the bloodstream instead of being absorbed into cells. This occurs when cells either lose their ability to produce the hormone insulin or, in type 2 diabetes, they develop insulin resistance and are unable to use it productively.
Over the years, researchers discovered certain factors increase the risk of developing type 2 diabetes. These potential risk factors include alcohol consumption, skipping breakfast, daytime napping, anxiety disorders, urinary sodium, certain amino acids and inflammatory factors, and lack of sleep.
A new study that appears in the journal Diabetologia identifies 19 risk factors for type 2 diabetes. The Sweden-based researchers further evaluated 21 risk factors that have scarce evidence, and another 15 that reduce the risk of the condition.
The team used a method called ‘Mendelian randomization’ (MR) to obtain their findings. This technique blends genetic information and conventional epidemiological methods. It also addresses questions related to causality without biases that could compromise the validity of epidemiological approaches.
Associate professor Susanna Larsson and Shuai Yuan of the Karolinska Institutet in Stockholm, Sweden, used data from the Diabetes Genetics Replication And Meta-analysis consortium. The duo evaluated 74,124 cases of type 2 diabetes and 824,006 control participants with European ancestry for the study population. The participants’ mean age was around 55 years, and 51.8% of them were male.
The researchers then screened 238 studies before including 40 individual papers in their MR investigation. Among the 97 factors they looked at, only 19 increased diabetes risk.
Insomnia was identified as a novel risk factor — people living with the condition are 17% more likely to develop type 2 diabetes than those without it.
Speaking with Medical News Today, Larsson says, “Daytime napping also appears to be a risk factor for type 2 diabetes. However, because it is strongly related to insomnia, it’s unclear whether daytime napping is an independent risk factor for type 2 diabetes.”
The other risk factors include:
- high blood pressure
- caffeine consumption
- childhood and adult obesity
- body fat percentage
- internal fat mass
- blood plasma levels of four saturated and polyunsaturated fatty acids
- blood plasma levels of three amino acids —valine, leucine, and isoleucine
- blood plasma levels of alanine aminotransferase, an enzyme that facilitates liver function
“It is important to highlight that obesity is still the predominant risk factor for type 2 diabetes. The observed association with insomnia was partially, but not fully mediated by obesity (higher body mass index),” adds Larsson. “The association between depression and type 2 diabetes might, in part, be mediated by insomnia.”
The exposures associated with a decreased risk of type 2 diabetes include:
- the amino acid, alanine
- high-density lipoproteins, or good cholesterol
- total cholesterol
- the age when females start menstruating
- testosterone levels
- birth weight
- adulthood height
- lean body mass for females
- four plasma fatty acids
- vitamin D
- education level
In their study, the authors further explain:
“Findings should inform public health policies for the primary prevention of type 2 diabetes. Prevention strategies should be constructed from multiple perspectives, such as lowering obesity and smoking rates and levels, and improving mental health, sleep quality, educational level, and birth weight.”
While the study’s findings offer important information that might be useful in drafting public health policies, its major limitation is the study population’s homogenous nature.
According to the IDF, 79% of adults with diabetes live in low- and middle-income countries. Studies have also found that the chance of developing diabetes is significantly higher for Black people — around 66 more cases of diabetes per 1,000 people — compared with white adults.
Larsson admits that major risk factors for type 2 diabetes might partly differ by ancestry. “Unfortunately, we were unable to […] perform similar analyses in populations of non-European ancestry,” she says.