medwireNews: Researchers find partial restoration of brain responses to hypoglycemia in people with type 1 diabetes who recover hypoglycemia awareness during a multifactorial intervention.
The study by Munachiso Nwokolo (King’s College London, UK) and colleagues involved 12 people with type 1 diabetes and impaired awareness of hypoglycemia (Gold score ≥4) whose awareness significantly improved following an intervention lasting up to 12 months.
The participants attended a structured education course such as DAFNE, if they had not recently done so, and were then supplied with an insulin pump with a low-glucose suspend system. They had weekly virtual meetings and once or twice monthly in-person contact with clinicians to review glucose monitoring data and address self-management issues.
Ten of the participants achieved the goal of avoiding blood glucose levels below 3.0 mmol/L (54 mg/dL) for 3 weeks, within an average of 7.3 months. The team stresses that the two participants who did not achieve this target nevertheless had no episodes of severe hypoglycemia during follow-up, and a reduced frequency of overall hypoglycemia.
Average Gold scores in the whole group fell from 6.0 to 4.1, and the reduction in hypoglycemia occurred without a significant change in glycated hemoglobin levels or in peak epinephrine levels during hypoglycemia.
All participants underwent brain scans to assess cerebral blood flow during experimental hypoglycemia, at baseline and again after meeting the study target or at 12 months if this did not occur.
This revealed increased blood flow during hypoglycemia to the left orbitofrontal cortex (OFC) and left dorsolateral prefrontal cortex (DLPFC) – both regions involved with executive function – along with decreases to the right temporal cortex.
The intervention made no apparent difference to the hypoglycemic-induced changes in blood flow to the OFC or DLPFC, nor within the thalamus, which the team notes is involved in “arousal, sensory and motor relay, and cortical signal transmission.”
However, participants had a significantly greater blood flow increase within the right anterior cingulate cortex after the intervention versus before it.
The researchers say this region is “involved in autonomic control, interoception (awareness of internal homoeostatic state), and complex decision making,” noting that it “is pivotal in evaluating events that require behavioral modification and monitoring performance and outcome.”
They add: “Lack of restoration of thalamic and frontal responses to hypoglycemia may still represent a predisposition to [impaired awareness of hypoglycemia] or that meticulous avoidance of hypoglycemia through education and technology is not sufficient to address cognitive or behavioral drivers of hypoglycemia awareness.”
Participants also had a trend toward larger hypoglycemia-induced decreases in left hippocampal blood flow after the intervention versus before, which the team says implies “partial recovery of typical hippocampal responses to hypoglycemia.
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Diabetes Care 2020; doi:10.2337/dc20-1250