Randomized, double-blind, crossover-trial, 30 subjects in each groups, either males or females, normal fasting glucose or pre-diabetes, aged > 18 years old to perform oral sucrose tolerance with either one of the 5 study products

1. Sucrose 50 g
2. Sucrose 50 g + D-allulose (psicose) 2.5 g
3. Sucrose 50 g + D-allulose (psicose) 5 g
4. Sucrose 50 g + D-allulose (psicose) 7.5 g
5. Sucrose 50 g + D-allulose (psicose) 10 g

Primary endpoints:

1. To investigate the dose-response effects of D- allulose (psicose) with sucrose beverage on glucose tolerance
2. To investigate the dose-response effects of D- allulose (psicose) with sucrose beverage on insulin levels

Objectives Primary objectives

1. To investigate the dose-response effects of D-allulose (psicose) with sucrose beverage on glucose tolerance
2. To investigate the dose-response effects of D-allulose (psicose) with sucrose beverage on insulin levels

Subjects and methods Study product A. Sucrose 50 g B. Sucrose 50 g + D-allulose (psicose) 2.5 g C. Sucrose 50 g + D-allulose (psicose) 5 g D. Sucrose 50 g + D-allulose (psicose) 7.5 g E. Sucrose 50 g + D-allulose (psicose) 10 g

Study plan Screening (visit 0)

• Obtain inform consent
• History taking for medical problems, smoking, alcoholic drinking, concurrent medication, contraception or menopausal status, weight history
• Measure body weight, height and calculated BMI
• Measure waist and hip circumference
• Body composition measurement by bioelectrical impedance analysis (BIA)
• Complete physical examination
• Urine pregnancy test in all female of childbearing potential
• Provide 24-hour food record
• Ask to come back within 1 week

Visit 1: (day 7 or 6-11 days)

• Complete physical examination
• Randomize subject to receive any 1 of 5 study products
• Perform OSTT with that product
• Return food record
• Provide 24-hour food record
• Adverse events evaluation
• Ask to come back within 7 +/- 4 days

Visit 2: (day 7 or 6-11 days from visit 1)

• Complete physical examination
• Randomize subject to receive any 1 of 4 study product which are left
• Perform OSTT with that product
• Return food record
• Provide 24-hour food record
• Adverse events evaluation
• Ask to come back within 7 +/- 4 days

Visit 3 (day 7 or 6-11 days from visit 2)

• Complete physical examination
• Randomize subject to receive any 1 of 3 study product which are left
• Perform OSTT with that product
• Return food record
• Provide 24-hour food record
• Adverse events evaluation
• Ask to come back within 7 +/- 4 days

Visit 4 (day 7 or 6-11 days from visit 3)

• Complete physical examination
• Randomize subject to receive any 1 of 2 study product which are left
• Perform OSTT with that product
• Return food record
• Provide 24-hour food record
• Adverse events evaluation
• Ask to come back within 7 +/- 4 days

Visit 5 (day 7 or 6-11 days from visit 4)

• Complete physical examination
• Perform OSTT with the product that is left
• Return food record
• Adverse events evaluation

Adverse Event Assessment At each visit, participants will be asked an open question as if he/she has experienced any abnormal symptoms. Any symptom reported by the participants will be recorded as an adverse events with details of the event, its severity, start and stop dates, and relationship to study products. Gastrointestinal symptoms (heartburn, distension, nausea, vomiting, abdominal pain, flatulence, constipation and diarrhea) within 24 hours after OSTT will be asked and recorded as well.

Withdrawal criteria

1. Those who are not able to complete 5 visits of OSTT within 8 weeks
2. Those who cannot provide 24-hour dietary record at each visit
3. Those who start any medication that might cause increasing in plasma glucose during participating in the study

Inclusion Criteria:

1. Male or female, age > 18 years and legal age of consent.
2. If female, the participant is either post-menopausal or surgically sterilized, or has a negative urine kit pregnancy test within 7 days prior to enrollment and will use adequate contraception during the study.
3. The participant has provided written informed consent prior to admission to the study.
4. Participant is able to join the entire study with 8 weeks.
5. Participant is able to keep 24-hour dietary record a day prior to each visit.

Exclusion Criteria:

1. Pregnancy or lactation
2. Diagnosed with diabetes mellitus
3. Those who take any medication that might be able to increase plasma glucose 1 month prior to the study or during in the study
4. Acute illness within 1 weeks prior to the study
5. Has gastrointestinal symptoms such as nausea, vomiting, loss of appetite, premature satiety, diarrhea, or chronic constipation
6. Immunocompromised status, including a debilitated state or malignancy
7. Active liver, renal, thyroid diseases
8. Lack of ability or willingness to give informed consent
9. Enrolled in any other clinical study within 3 months before enrolment
10. Any people whose life style is irregular, for example, person works at night shifts.