Measuring visual cortical oxygenation in diabetes using functional near-infrared spectroscopy

Area of Science:

• Neuroscience
• Diabetology
• Medical Imaging

Background:

• Diabetes mellitus impacts global health, affecting approximately 6% of the population.
• Chronic diabetes complications can lead to significant macro- and micro-vascular damage.
• Understanding vascular changes in the brain, specifically visual cortex oxygenation, is crucial in diabetes management.

Purpose of the Study:

• To investigate visual cortical oxygenation in individuals with diabetes mellitus.
• To compare the hemodynamic response (HDR) to visual stimulation between diabetic and non-diabetic individuals.
• To correlate the HDR with glycemic control, specifically HbA1c levels.

Main Methods:

• Exploratory study involving 30 participants: 15 with diabetes and 15 healthy controls.
• Functional near-infrared spectroscopy (fNIRS) used to measure oxyhaemoglobin [HbO] and deoxyhaemoglobin [HbR] concentrations in the primary visual cortex (V1) during visual stimulation.
• Analysis of normalized haemodynamic data, including comparison of mean HbA1c levels between groups.

Main Results:

• Statistically significant differences in ∆[HbO] and ∆[HbR] during visual stimulation were observed between diabetic and non-diabetic groups (p < 0.05).
• Type 1 diabetes patients showed increased [HbO] (p < 0.01) and decreased [HbR] (p < 0.05) compared to type 2 diabetes patients.
• A strong linear relationship was found between both ∆[HbO] and ∆[HbR] and HbA1c levels (p < 0.0005).

Conclusions:

• fNIRS serves as a viable quantitative tool for assessing cortical oxygenation in diabetes.
• Diabetic individuals demonstrate an amplified hemodynamic response to visual stimuli compared to non-diabetics.
• The observed alterations in cortical oxygenation are significantly correlated with the level of glycemic control (HbA1c).