Objective:Characterizing blood glucose curves and providing precise patient level
risk assessment of hyperglycemia using extreme value statistics and comparing these
assessments with traditional indicators of glycemic variability which are not designed
to specifically capture the risk of hyperglycemia.Research Design and Methods:One
year return level (blood glucose level exceeded exactly once every year on average)
and probability of exceeding and expected time spent above certain thresholds (600
and 400 mg/dL) per year were calculated. As a comparison, traditional metrics for
glycemic variability were determined too. The effect of body mass index on extremes
was also investigated using non-stationary models. Metrics were calculated on a dataset
containing 170.8 patient-years of measurements of 226 patients.Results:Nine high-risk
patients were identified with the novel metrics: their estimated time spent above
600 mg/dL per year were above 2 hours. These patients were at moderate risk according
to the traditional metrics. Higher body mass index was associated with more extreme
glucose levels.Conclusions:Through these estimates it is possible to assess each patient?s
individual clinical risk of hyperglycemia even beyond the observed blood glucose levels
and detection limits. Additionally, it allows the assessment of the impact of clinical
characteristics and treatments on blood glucose control in a novel, mathematically
well-founded and potentially clinically more useful way than the already existing
indicators.
