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Brain Damage Associated with High Blood Glucose

Feb 16, 2021
Editor: Steve Freed, R.PH., CDE

Author: Brianna Belton, PharmD. Candidate, Florida Agricultural & Mechanical University, College of Pharmacy and Pharmaceutical Sciences

Researchers continue to uncover the many ways uncontrolled hyperglycemia in diabetes can damage the body, including the brain. 

Diabetes, if left uncontrolled, can lead to very debilitating complications. Prolonged high levels of glucose in the blood cause the blood to thicken and slow down. The body is not being adequately perfused, leading to strokes, slow wound healing, and possibly amputations. The thicker the blood, the higher the blood pressure, which can lead to blindness and hypertension. Now, the body is in overdrive to try to get rid of this extra glucose in the blood, which in turn burns out the kidneys, leading to damage. With all of the damage done due to uncontrolled diabetes, new research now includes brain damage resulting from uncontrolled type 2 diabetes. However, diabetes does not always have to lead to detrimental results; if properly managed, patients can live long and healthy lives.  


In a study of 49 patients with type 2 diabetes, 15 patients with an HbA1C < 7% (the controlled type 2 diabetes group), and 22 patients with an HbA1C > 7% (the uncontrolled type 2 diabetes group), were both compared to 12 healthy patients, the control group. Images of the brain and the “whole-brain mean diffusivity (M.D.)” were gathered from all patients with the use of magnetic resonance imaging (MRI) of different brain areas. M.D. is used to localize lesions in the brain. The patients with uncontrolled type 2 diabetes displayed increased M.D. values in multiple brain areas compared to the controlled type 2 diabetes patients and the control group. The more affected brain areas were associated with cognition and mood. 

The authors concluded that higher HbA1c levels are associated with more significant risks of brain damage. The brain areas that are more likely to be affected are the areas that help regulate cognitive function. The authors also noted that the brain injury due to hyperglycemia might further reduce the patient’s ability to control their blood glucose levels, leading to higher chances of patients experiencing prolonged uncontrolled type 2 diabetes and the risks associated with it. 

This study evaluating the effect of blood glucose on brain function only included 49 patients. More subjects would increase the ability of researchers to generalize the results. Further research is also needed to confirm the data presented in this study. Additionally, the study only included patients with type 2 diabetes. The results could vary for patients with type 1 diabetes. Patients in this study were also around the age of 50 years old. Over 30 million Americans of all ages are currently diagnosed with diabetes, with 88 million having prediabetes. Diabetes does not discriminate. Therefore, with the growing prevalence and incidence of diabetes, patients as young as ten can have type 2 diabetes and should be considered in these findings and future research. This a good first step to identify more complications associated with diabetes, and to stress the importance of properly managing diabetes.  

The results presented are leaning towards patients with uncontrolled type 2 diabetes. The patients without type 2 diabetes and even those with controlled type 2 diabetes did not present with increased M.D. values. This shows how important it is to control blood glucose due to the domino effect that uncontrolled diabetes causes over time. Even though a patient may be diagnosed with type 2 diabetes, it does not mean that these complications have to happen. However, it does mean that these patients are at a higher risk for such complications and have to take more steps to improve their health with their healthcare team’s help 

Practice Pearls: 

  • New research has shown that uncontrolled type 2 diabetes can lead to brain damage, particularly in areas of the brain associated with cognitive function, including mood.  
  • The complications associated with uncontrolled hyperglycemia are extensive and continuously being uncovered. There are probably more things that are still unknown that unchecked type 2 diabetes can potentially lead to. 
  • Glycemic control is essential.  
  • To determine the validity of the results presented, more studies have to be done and even expanded to include patients with type 1 diabetes and different age groups.  


Ph.D., M. (2020, July 07). Research Shows High Blood Sugar Can Cause Brain Damage (ADA 2020). Retrieved July 18, 2020, from https://www.diabetesdaily.com/blog/research-shows-high-blood-sugar-can-cause-brain-damage-ada-2020-660359/ 

Complications ADA. (n.d.). Retrieved July 18, 2020, from https://www.diabetes.org/diabetes/complications 


Brianna Belton, PharmD. Candidate, Florida Agricultural & Mechanical University, College of Pharmacy and Pharmaceutical Sciences