Internet-based pilot study comparing low fat with high fat evening snacks in children and adolescents with Type 1 Diabetes using continuous glucose monitoring.

Darrell M. Wilson1, Kimberly Caswell1, H. Peter Chase2, Michael Tansey3, Larry A. Fox4, Stuart Weinzimer5, Dongyuan Xing6, Roy Beck6, Craig Kollman6, William Tamborlane5, Katrina Ruedy6 and the Diabetes Research in Children Network (DirecNet) Study Group. 1Stanford, CA; 2Denver, CO; 3Iowa City, IA; 4Jacksonville, FL; 5New Haven, CT; 6Tampa, FL

Introduction: Bedtime snacks are frequently employed in the treatment of children with type 1 diabetes to prevent nocturnal hypoglycemia, and the inclusion of protein and/or fat is commonly recommended.

Methods: Ten subjects with T1DM (age 6-18y, HbA1c 6.9 ± 0.5%) enrolled in a pilot trial evaluating the Navigator glucose sensor completed a study comparing the effect of bedtime snack fat content on nocturnal hypoglycemia. On ≥12 separate nights, each subject received either a low-fat (30 gm carbohydrate, 3 gm protein, 1 gm fat; 138 kCal) or high-fat (30 gm CHO, 2 gm protein, 20 gm fat; 320 kCal) snack in random order. Subjects checked their glucose and via a website, were assigned to a high or low fat snack. Subjects used their usual evening snack algorithm to determine the size (in 15 gram carbohydrate increments). Data were from nights with at least 5h (average of 8.1±1.3h) of sensor data after the snack.

Results: Average BG (mg/dl) on 128 valid study nights before snack were similar in both groups (163 ± 55, high fat; 164±53, low fat). The proportion of nights with hypoglycemia (sensor glucose ≤70) was similar in both groups (23% high fat vs 21% low fat). Likewise, the proportion of nights with hyperglycemia (sensor glucose ≥200) was similar in both groups (68% high fat vs 61% low fat). Conclusion: Even very well controlled children and adolescents with T1DM have a very high frequency of high and low glucose levels. However, the altering the amount of fat in the bedtime snack had no impact on frequency of hyperglycemia or hypoglycemia. This study also highlights the feasibility of web based research in patients’ home environment.

Abstract

Background

• Hypoglycemia is a frequent and potentially serious complication of intensive insulin therapy, particularly in children with type 1 diabetes

• Almost half of severe hypoglycemia episodes occur overnight, while children are not being actively supervised or monitored

• Common practice suggests the ingestion of a fat-containing bedtime snack may reduce the risk of nocturnal hypoglycemia, presumably via delaying carbohydrate absorption

Rationale

• The purpose of this outpatient study was to determine whether, among children with type 1 diabetes (T1DM) utilizing insulin pump, a pre-bedtime snack with a relatively high fat content provides greater protection from nocturnal hypoglycemia than a snack containing the same amount of carbohydrate and protein, but a lower fat content.

Methods - Subjects

• Ten subjects 6-<18 years old with T1DM for over a year and using an insulin infusion pump

• Mean hemoglobin A1C - 6.9%• Enrolled in a pilot trial evaluating the Abbott

Navigator ® Continuous Glucose Monitoring System

• On ≥12 nights, subjects were randomized to a carbohydrate snack or a carbohydrate plus fat snack

Sensor Delivery UnitReceiverTransmitterSensor

Abbott FreeStyle Navigator Sensor

Snacks

LOW FAT

30 gm CHO2.5 gm protein

1.3 gm fat138 kCal

HIGH FAT

30 gm CHO2 gm protein20 gm fat320 kCal

Web-based Snack Assignment and Data Collection

• Subjects logged on the study website and– entered the pre-snack glucose level– entered the level of activity during that day– used usual practices for determining the amount

of carbohydrate (in 15-gram increments) – entered the amount of insulin to be taken to cover

the snack• A minimization algorithm was used to

determine the order of the snack types based on– the pre-snack meter glucose level– the self-reported amount of activity during that

day

Web-based Snack Assignment and Data Collection

Web-based Snack Assignment and Data Collection

Outcome Measures

• The primary outcome was hypoglycemia– at least one glucose value ≤70 mg/dL on either the

Navigator or the FreeStyle meter

• Hyperglycemia was defined as at least one glucose value ≥200 mg/dL and at least 50 mg/dL above pre-snack glucose on either the Navigator or the FreeStyle meter.

• At least 12 nights with at least 5 hours of sensor data were collected

ResultsHigh fat Low fat

Nights (#) 62 66

Pre-snack Meter Glucose (M±SD) 163 ± 55 164 ± 53

Pre-snack Sensor Glucose (M±SD) 162 ± 60 165 ± 54

Mean Sensor Glucose Overnight * (M±SD) 171 ± 46 156 ± 45

Hypoglycemia #(%) 12 (19%) 13 (20%)

Hyperglycemia #(%) 22 (35%) 20 (30%)

*p-value=0.02

Time to Hyperglycemia for the high-fat and low-fat Nights. Hyperglycemia was defined as the first glucose value ≥200 mg/dL and at least 50 mg/dL abovepre-snack Navigator glucose.*p-value from permutation test to account for correlated data from the same subject

0%

5%

10%

15%

20%

25%

30%

35%

40%

0 1 2 3 4 5 6 7 8 9

Hours from Bedtime Snack

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Low Fat N=66

High Fat N=62

p-value=0.61 *

Time to Hypoglycemia for the high-fat and low-fat Nights. Hypoglycemiawas defined as the first glucose value ≤70 mg/dL. *p-value from permutation test to account for correlated data from the same subject

0%

5%

10%

15%

20%

25%

30%

35%

40%

0 1 2 3 4 5 6 7 8 9

Hours from Bedtime Snack

Cu

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lati

ve

Pro

ba

bili

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yp

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Low Fat N=66

High Fat N=62

p-value=0.93*

The Mean Sensor glucose value at each hour in each group after bedtime snack.BG at baseline (hour zero) is the average sensor reading over the 30 minutes prior to the snack.BG at each hour after snack is the average of sensor readings within ± 15 minutes of the hour*p-value<0.01 at 5 hours after snack

140

160

180

200

0 1 2 3 4 5 6 7 8

Hours from Bedtime Snack

Me

an

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Glu

co

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(m

g/d

L)

High Fat

Low Fat

*

Results

• There were no meaningful differences between the high and low fat snacks on the frequency of hyperglycemia or hypoglycemia. – Mean overnight glucoses were higher in the high

fat snack

• There was no meaningful difference in the timing of hyper- or hypoglycemia

• This study highlights the feasibility of web- based research in patients’ home environment.

Discussion

• The addition of fat to a bedtime snack does not improve overnight glycemic control and may cause hyperglycemia

• This study demonstrates the utility of web-based randomization and data collection systems in examining clinically important outpatient problems in patients with chronic diseases.