  Background: This study investigates glucose conditions preceding and
following various hypoglycemia levels in individuals with type 1 diabetes using
open-source automated insulin delivery (AID) systems. It also seeks to evaluate
relationships between hypoglycemia and subsequent glycemic variability.
Methods: Analysis of continuous glucose monitor (CGM) data from 122 individuals
with type 1 diabetes using open-source AID from the OpenAPS Data Commons was
conducted. The study comprehensively analyzed the effects of hypoglycemia on
glycemic variability, covering time periods before and after hypoglycemia.
Results: Glucose variability normalization post-hypoglycemia can take up to 48
hours, with severe hypoglycemia (40-50 mg/dL) linked to prolonged
normalization. A cyclical pattern was observed where hypoglycemia predisposes
individuals to further hypoglycemia, even with AID system use. A rise in
glucose levels often precedes hypoglycemia, followed by an elevated mean time
above range (TAR) post-severe hypoglycemia, indicating a 'rebound' effect.
Different hypoglycemia categorization approaches did not show significant
differences in glycemic variability outcomes. The level of hypoglycemia does
influence the pattern of subsequent glucose fluctuations. Conclusion:
Hypoglycemia, especially at lower levels, significantly impact subsequent
glycemic variability, even with use of AID systems. This should be studied
further with a broader set of commercial AID systems to understand if these
patterns are true of all types of AID systems. If these patterns occur in all
types of AID systems, it underscores potential opportunities for enhancements
in AID algorithms and highlights the importance of educating healthcare
providers and people with diabetes about post-hypoglycemia glucose variability.
