We know that diabetes affects our entire physical bodies: our nervous system, our digestive system, and even our vision. Diabetes is even linked to depression because of the stress and isolation associated with the disease. But research is becoming more and more clear that there is also a link between type 2 diabetes and declining brain function over time.
While earlier studies discussed a clear correlation between diabetes and reduced cognitive function and made speculations about the causality, a recent study has made a stronger connection. The UK-based study found that there are “significant” connections between HbA1c levels, diabetes status, and cognitive decline, especially in the areas of memory and executive function (executive function refers to self- and resource-management in order to achieve a goal).
An older study, published in 2014, examined the significance of several risk factors for cognitive decline that are associated with type 2 diabetes in an attempt to better understand the rising prevalence of type 2 diabetes concurrently with Alzheimer’s disease and vascular dementia. The study theorized that diabetes-related hyperglycemia was causing cognitive decline, but concluded that, “Overall, the association of type 2 diabetes with increased cognitive impairment appears to be relatively weak before the age of 70 years, provided that good glycemic control is maintained, and it is only in older patients that cognitive decrements related to chronic hyperglycemia become apparent.”
Researchers did note that poor mid-life glycemic control was related to late-life cognitive impairment, and if diabetics wait until signs of cognitive decline manifest in order to implement more aggressive glucose management, the damage may have already been done. But the 2014 study still left a lot of questions unanswered, or answered only vaguely.
The more recent study, published in early 2018 and examining over 5,100 participants, is much more clear. This study found significant, long-term connections between elevated HbA1c levels, diabetes status, and cognitive decline. And it’s not just relevant to those with diagnosed diabetes; because the danger stems from high blood sugar, those with prediabetes are also affected. The study analysis in Forbes noted that there is a clear “linear correlation between circulating HbA1c levels and cognitive decline.” In other words, risk for cognitive decline rises with the frequency and intensity of high blood sugar.
Study results showed that those with prediabetes or diabetes had decreased scores on cognitive tests over the 8-year study period. Participants were assessed at the beginning of the study and then again every two years. All study participants experienced some cognitive decline as a normal part of aging, but the test scores for those with prediabetes or diabetes declined more significantly and more rapidly than the those in the control group—even when accounting for lifestyle factors and demographics.
There was some good news. The researchers noted, “Our findings suggest that interventions that delay diabetes onset, as well as management strategies for blood sugar control, might help alleviate the progression of subsequent cognitive decline over the long-term.”
So there is now additional motivation for those with diabetes, or even prediabetes, to manage their blood sugar as much as possible: their brain may depend on it.
While managing blood sugar is hardly as simple of flipping a switch, lifestyle changes can positively affect blood sugar, and prolonging proper brain function is certainly significant motivation.
Katie Taylor started writing in 5th grade and hasn't stopped since. Her favorite place to pen a phrase is in front of her fireplace with a cup of tea, but she's been known to write in parking lots on the backs of old receipts if necessary. She and her husband live cozily in the Pacific Northwest enjoying rainy days and Netflix.