Brain atrophy is associated with blood sugar on the higher end of normal

Brain atrophy, or the loss of brain mass due to accelerated neurodegeneration, is the gross anatomical aspect of cognitive impairment and dementia. There is abundant evidence that blood sugar and insulin dysregulation are harmful to the brain. A paper just published in the journal Neurology shows that even plasma glucose ('blood sugar') in the higher end of the 'normal' range is associated with brain atrophy. The authors state:

"Substantial evidence showing an association between type 2 diabetes (T2D) and cerebral atrophy, cognitive impairment, and dementia is accumulating. However, relatively little is known about the subclinical effects of high plasma glucose levels within the normal range. The aim of this study was to investigate the association between plasma glucose levels and hippocampal and amygdalar atrophy in a sample of 266 cognitively healthy individuals free of T2D, aged 60–64 years, taking part in a longitudinal study of aging."

The hippocampus is the brain's 'center' for short-term memory and adrenocortical regulation, and the amygdala modulates memory and emotional learning. The authors correlated fasting plasma glucose levels with the volumes of the hippocampus and amygdala determined by MRI at the beginning of the study and 4 years later. There was a strong association of plasma glucose and brain atrophy:

"Plasma glucose levels were found to be significantly associated with hippocampal and amygdalar atrophy and accounted for 6%–10% in volume change after controlling for age, sex, body mass index, hypertension, alcohol, and smoking."

This finding has great practical significance for the prevention and treatment of brain-based disorders. The health effects of brain atrophy are global and impair health and quality of life in a multitude of ways because the brain is the regulator of systemic physiology as well as the organ of cognition. The subjects in this study were not diabetic, their fasting plasma glucose was higher but still in the normal ranges. Astute clinicians know, however, that well before the onset of type 2 diabetes rising insulin levels do insidious damage throughout the body. Moreover, the factors contributing to this, including increased inflammation, can harm the brain and other tissues on their own. The authors conclude:

"High plasma glucose levels within the normal range (<6.1 mmol/L) were associated with greater atrophy of structures relevant to aging and neurodegenerative processes, the hippocampus and amygdala. These findings suggest that even in the subclinical range and in the absence of diabetes, monitoring and management of plasma glucose levels could have an impact on cerebral health. If replicated, this finding may contribute to a reevaluation of the concept of normal blood glucose levels and the definition of diabetes."

Insulin resistance and hypoglycemia both contribute to chronic inflammation. Clinicians should offer education for lifestyle factors and interventions based on the objective tests to determine strategies for healthy insulin and plasma glucose tuned to the individual.Note: 6.1 mmol/L of glucose converts to 109.91 mg/dL.