Introduction
Iatrogenic hypoglycemia remains one of the leading hindrances of optimal glycemic management in insulin-treated diabetes. Recurring hypoglycemia leads to a condition of hypoglycemia-associated autonomic failure (HAAF). HAAF refers to a combination of (i) impaired hormonal counter regulatory responses and (ii) hypoglycemia unawareness to subsequent hypoglycemia, substantially increasing the risk of severe hypoglycemia. Several studies since the 1990ies have experimentally induced HAAF yielding variable results. The aim of this review is to assess the varying designs, clinical outcomes, potential assets and drawbacks related to these studies.
Method
A systemic literature search was conducted on PubMed and Embase in the winter 2021 to include all human studies which attempting to experimentally induce HAAF. In different combinations, the search terms used were “hypoglycemia-associated autonomic failure", “HAAF”, “hypoglycemia” “recurring”, “recurrent”, “repeated”, “consecutive”, and “unawareness” yielding 1,565 publications. Inclusion criteria were studies who had aimed at experimentally inducing HAAF and measuring outcomes of hormonal counter regulation and awareness of hypoglycemia.
Results
The literature search yielded 27 eligible publications of which 20 were successful in inducing HAAF with statistical significantly impairing both hormonal counter regulation and impairing awareness of hypoglycemia to subsequent hypoglycemia. Several factors were of significance as regards inducing HAAF; foremost, the duration of antecedent hypoglycemia should be at least 90 minutes and blood glucose should be maintained below 3.4 mmol/L. Other important factors to consider are the type of participants, insulin dosage, and the risk of unintended hypoglycemia prior to the study.
Conclusion
Here we have outlined the most important factors to take into consideration when designing a study aimed at inducing HAAF including to take into consideration other disease states susceptible to hypoglycemia thus hopefully clarifying the field and allowing qualified studies in the future.