Mealtime Glycemic Excursions in Pediatric Subjects with Type 1 Diabetes: Results of the Diabetes Res

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Mealtime Glycemic Excursions in Pediatric
Subjects with Type 1 Diabetes Results of the
Diabetes Research in Children (DirecNet) Accuracy
Study
Study Group
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Background

• The Diabetes Research in Children Network
  (DirecNet) is a multi-center group whose aim is
  to study the accuracy and practicability of
  glucose sensor systems in children with type 1
  diabetes (T1DM)
• Meal-related hyperglycemic excursions contribute
  greatly to difficulty in optimal diabetes control
• Continuous glucose monitoring systems provide the
  opportunity to study meal-related glucose
  excursions

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Objectives

• To describe meal-related glycemic excursions in
  children and adolescents with T1DM
• To determine the accuracy of the Continuous
  Glucose Monitoring System (CGMS, Medtronic
  MiniMed, Inc.) and the GlucoWatch G2 Biographer
  (GW2B, Cygnus, Inc.) under rapidly changing
  glucose levels

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Methods

• 82 children with T1DM admitted to 5 CRCs
• CGMS, GW2B, blood-drawing IV inserted
• Short-acting or meal-related bolus insulin
  omitted
• Standard liquid carbohydrate meal administered,
  1.75 gm/kg (max 75 gm)
• Reference venous blood glucose (BG) measured at
  baseline and every 5 min for up to 60 min
• Sensor glucose (SG) levels compared to reference
  BG

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Subject Demographics
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Clinical Characteristics
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BG Distribution at each 5-minute interval during
meal-induced Hyperglycemia test
500
400
300
Glucose (mg/dL)
200
100
0
0 5 10 15 20 25 30
35 40 45 50 55
Time since start of test (min)
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Baseline and Peak Glucose Levels by Age and
Treatment Modality
Height of bar mean Whisker mean 1 SD
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Time Course of Glucose Excursion by Age and
Treatment Modality
Time to peak BG (min)
Height of bar mean Whisker mean 1 SD
Restricted to n62 subjects in whom hyperglycemia
was successfully induced (increase of 100 mg/dL
or doubling from baseline)
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Sensor Accuracy According to Rate of Glucose
Change During Test
Median Relative Absolute Deviation
Rate of Change (mg/dL per min)
Accuracy did not vary by rate of
change. Calculated from the previous reference
glucose value (drop in BG divided by minutes
between values)
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Fulfillment of ISO Criteria According to Rate of
Glucose Change During Test
Meeting ISO Criteria
Rate of Change (mg/dL per min)
Accuracy did not vary by rate of change ISO
criteria for reference BG 75 mg/dL, SG within
15 mg/dL for reference BG gt75 mg/dL, SG value
within 20
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Conclusions

• Magnitude, timing, and rate of meal-related
  hyperglycemic excursions were consistent across
  all age groups
• Sensor accuracy was not affected by rapid
  increases in BG levels
• Sensor performance during rapid glucose changes
  met ISO criteria for 51-72 of SG readings

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• Stanford University
• Bruce Buckingham
• Darrell Wilson
• Jennifer Block
• Yale University
• William Tamborlane
• Stuart Weinzimer
• Elizabeth Boland
• Jaeb Center for Health Research
• Roy Beck
• Katrina Ruedy
• Craig Kollman
• Andrea Booth
• Gladys Bernett

• Barbara Davis Center
• H. Peter Chase
• Rosanna Fiallo-Scharer
• Jennifer Fisher
• University of Iowa
• Eva Tsalikian
• Michael Tansey
• Linda Larson
• Nemours Childrens Clinic
• Tim Wysocki
• Nelly Mauras
• Kristen Gagnon

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Abstract

• Mealtime Glycemic Excursions in Pediatric
  Subjects with Type 1 Diabetes Mellitus (T1DM)
  the DirecNet Experience
• Stuart Weinzimer1, Roy Beck2, Katrina Ruedy2,
  Andrea Booth2, Elizabeth Boland1, and the
  Diabetes Research in Children Network (DirecNet)
  Study Group. 1Department of Pediatrics, Yale
  University School of Medicine, New Haven, CT and
  2Jaeb Center for Health Research, Tampa, FL.
• Background DirecNet is a multi-center network
  whose aim is to study glucose sensing systems in
  children with T1DM. A meal protocol, in which a
  standard carbohydrate load was administered to
  test the accuracy of these sensors during
  changing blood glucose (BG) conditions, provided
  the opportunity to study the magnitude and timing
  of hyperglycemic excursions in children with
  T1DM. Objective To describe the BG excursions in
  children with T1DM after a standard meal
  challenge and determine their relationship to
  patient factors. Design/Methods 82 subjects with
  T1DM (41F, 41M, mean age 10?4 y range 3-17 y)
  were admitted to the CRC for metabolic
  monitoring. After oral ingestion of a standard
  liquid simple carbohydrate meal (1.75 gm/kg,
  maximum 75 gm), venous BG measurements were
  obtained at baseline and every 5 minutes for up
  to 60 minutes. Subjects using multiple daily
  injections (MDI) delayed their insulin injection,
  and pump subjects continued basal insulin
  delivery but delayed bolus insulin, until meal
  test completion. Results BG increased from a
  mean baseline of 148?65 mg/dL to a peak of 283?78
  mg/dL. Mean time to peak BG was 56?9 min. Among
  subjects who increased at least 100 mg/dL or 100
  from baseline (N62), mean rate of rise of BG was
  3.4?1.1 mg/dL-min from start of increase to peak
  glucose. Magnitude of time to glucose peak, and
  rate of change of blood glucose were similar
  comparing the MDI and insulin pump-treated
  subjects. Conclusions This standardized
  carbohydrate load induced a large hyperglycemic
  excursion, which was relatively consistent across
  all age groups and treatment modalities.
  Notably, the timing of BG rise was slower than
  anticipated, particularly in the first 15
  minutes, which has important therapeutic
  implications regarding conventional treatment of
  hypoglycemia in T1DM with oral carbohydrates.