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Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Type of registration
Retrospectively registered

Titles & IDs
Public title
The effect of meal timing on postprandial glucose in healthy volunteers
Scientific title
The effect of meal timing on postprandial glucose in healthy volunteers
Secondary ID [1] 288278 0
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
postprandial glucose 297235 0
Type 2 Diabetes 297236 0
Condition category
Condition code
Diet and Nutrition 297441 297441 0 0
Other diet and nutrition disorders

Study type
Description of intervention(s) / exposure
Part one – OGTT
After a ten hour fast participants will report to the BASE facility at either 0730h (morning) or 1930h (evening). Anthropometric measures (height, weight, blood pressure, waist circumference and blood pressure) will be obtained by a researcher and two blood samples for fasting glucose (finger prick) will be taken at time -15 mins and time 0 mins. A glucose solution made from pure glucose powder (75g in 400 ml water) will be provided at 0800h or 2000 hrs and participants asked to consume this within five minutes. Blood sampling (finger prick) for glucose assessment will be collected at the following time points over a two hour period (15, 30, 45, 60, 90, 120 mins). Washout between study days is a minimum of three days.

Part two – Low GI meal
Part two replicates part one except an Intravenous cannula will be inserted by an experienced nurse or phlebotomist thirty minutes before the start of the trial. One baseline blood sample will be taken at time 0 mins followed by a low GI meal at 0800h or 2000h which participants will be asked to consume within 15 minutes. Blood sampling will be collected at 15, 30, 45, 60, 9, 120 and 180 mins for glucose and insulin. Participants are able to opt in to a third time point where they will consume the same GI meal at midnight. The washout period between each of the meal occasions is a minimum of three days.
The low glycaemic index meal is a vegetarian pasta dish which consists of of 3.28MJ, with 47% Energy (E) from carbohydrate, 40%E from fat and 11%E from protein.
Intervention code [1] 293572 0
Comparator / control treatment
Comparator is the OGTT/meal in the evening compared to the morning
Control group

Primary outcome [1] 296997 0
Glucose (incremental area under the curve) is assessed from blood samples (finger prick in part one and venous blood in study two)
Timepoint [1] 296997 0
Two hour glucose iAUC will be calculated from finger prick blood samples at seven time points (-10, 0, 15, 30, 45, 60, 90 and 120 mins) after the OGTT (part one). Please note the -10 sample and 0 min sample will be averaged.
Three hour glucose iAUC will be calculated from venous blood samples at nine time points (0, 15, 30, 45, 60, 90, 120, 150 and 180 mins) after the low GI meal (part two)
Secondary outcome [1] 319820 0

Insulin (incremental area under the curve) is assessed from blood samples (finger prick in part one and venous blood in study two)
Timepoint [1] 319820 0
Three hour insulin iAUC will be calculated from venous blood samples at nine time points (0, 15, 30, 45, 60, 90, 120, 150 and 180 mins) after the low GI meal (part two)

Samples were not collected for insulin in part one (OGTT)

Key inclusion criteria
Healthy adults (18-50 years) who do not currently engage in shift work and have regular sleeping patterns
Minimum age
18 Years
Maximum age
50 Years
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
Currently shift workers or night workers
Age: > 50 years
Body mass index: <18.5 and > 30
Diagnosed with type 2 diabetes or taking anti-diabetic medication (oral hypoglycaemic agents)
Impaired fasting glucose
Taking lipid-lowering medication

Study design
Purpose of the study
Allocation to intervention
Non-randomised trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Masking / blinding
Open (masking not used)
Who is / are masked / blinded?

Intervention assignment
Other design features
The study is divided into two parts both of which involve undergoing an OGTT (part one) or consuming a low GI meal (part two) at two time points (8am and 8pm).
Part one is completed before part two
After completing part two (low GI meal), participants are given the opportunity to complete an additional time point at midnight. If this option is taken up it would mean that there are three timepoints in the low GI meal part (8am, 8pm and 1200 midnight)

Part two has an opt in to undertaking a third postprandial meal challenge at midnight
Not Applicable
Type of endpoint(s)
Statistical methods / analysis
Incremental area under the curve for glucose response will be the primary outcome measure for both parts of the study but data will not be compared between parts one and two as the starting carbohydrate load is not equivalent. Glucose response over the postprandial period will be estimated using incremental area under the response curve (iAUC). The iAUC will be calculated by the trapezoid rule, which ignores the area beneath the fasting level.. Insulin response (secondary outcome) will be assessed as iAUC as per glucose but only in part two if the study (not collected in part one).
Due to the small sample size required for this study, all data will be reported as median (interquartile range), except for the postprandial glucose and insulin time course graphs which will be presented as mean +/- SEM. Wilcoxon signed-rank test will be used used to determine the difference in 1) iAUC, 2) concentration at the end of postprandial period occasion and 3) fasting level, between morning and night occasions. Statistical significance was considered at p<0.05. Statistical analyses were conducted using Statistical Package for Social Sciences (SPSS) (version 21.0, IBM Corp., New York).

Nine participants were required, to provide 80% power and detect a mean difference of 15% in glucose concentration (total area under response curve) at an alpha value of 0.05. Sample size calculations were based on data from a study (Al-Naimi et al, 2004) that administered meals at 1300h (day time point) and at 0100h (night time point).
Al-Naimi S, Hampton SM, Richard P, Tzung C, Morgan LM. Postprandial metabolic profiles following meals and snacks eaten during simulated night and day shift work. Chronobiol. Int. 2004;21:937-947
To allow for drop outs, we plan to recruit 12 participants

Recruitment status
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment in Australia
Recruitment state(s)

Funding & Sponsors
Funding source category [1] 292657 0
Name [1] 292657 0
Monash University
Address [1] 292657 0
Wellington Road
Country [1] 292657 0
Primary sponsor type
Dr Maxine Bonham
Department of Nutrition and Dietetics,
Monash University
Level 1
264 Ferntree Gully Road
Notting Hill
Secondary sponsor category [1] 291375 0
Name [1] 291375 0
Address [1] 291375 0
Country [1] 291375 0

Ethics approval
Ethics application status
Ethics committee name [1] 294130 0
Monash University HREC
Ethics committee address [1] 294130 0
First Floor, Room 111
Chancellery Building E
24 Sports Walk
Monash Research Office
Clayton Campus
Monash University VIC 3800
Ethics committee country [1] 294130 0
Date submitted for ethics approval [1] 294130 0
Approval date [1] 294130 0
Ethics approval number [1] 294130 0
CF15/1301 - 2015000620

Brief summary
There is some evidence to suggest that the timing of a meal intake directly impacts postprandial insulin and glucose responses with meals consumed later during the day being more metabolically detrimental that the same meals consumed during the day. This information is particularly pertinent to the 16% of people employed in shift-work professions in Australia who have little choice but to eat during the late evening and overnight. The purpose of this study, therefore, is twofold. We propose to compare postprandial glucose and insulin responses following 1) an oral glucose tolerance test (OGTT) in the morning and in the evening followed by 2) a meal low in GI (glycaemic index) in the morning and the evening in healthy adults. These studies will enable us to confirm differences in metabolic functioning after eating at different times during the day using a standard test (OGTT) and then whether provision of a meal (low GI), thought to reduce postprandial insulin and glucose , will improve the unavoidable consequences of of eating at night on postprandial insulin and glucose.
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 62610 0
A/Prof Maxine Bonham
Address 62610 0
Monash University
Department of Nutrition and Dietetics
Level 1
264 Ferntree Gully Road
Notting Hill
Country 62610 0
Phone 62610 0
+61 3 99024272
Fax 62610 0
Email 62610 0
Contact person for public queries
Name 62611 0
A/Prof Maxine Bonham
Address 62611 0
Monash University
Department of Nutrition and Dietetics
Level 1
264 Ferntree Gully Road
Notting Hill
Country 62611 0
Phone 62611 0
+61 3 99024272
Fax 62611 0
Email 62611 0
Contact person for scientific queries
Name 62612 0
A/Prof Maxine Bonham
Address 62612 0
Monash University
Department of Nutrition and Dietetics
Level 1
264 Ferntree Gully Road
Notting Hill
Country 62612 0
Phone 62612 0
+61 3 99024272
Fax 62612 0
Email 62612 0

No information has been provided regarding IPD availability
Summary results
No Results