This study aims to test the following hypothesis in healthy lean young men:

• There are differences in glycemic response (GR) and insulin response (IR) between Chinese, Malay and Asian-Indian
• There are differences in GI values to the same food between ethnic groups
• There are ethnic differences postprandial GR and IR for high vs low GI foods
• Mastication, salivary amylase activity, gastric emptying rate and gut microbiota composition influences inter-individual glycemic and insulinemic variability
• Ethnic differences in mastication, salivary amylase activity, gastric emptying rate and gut microbiota composition determines the inter-ethnic glycemic and insulinemic variability

There is extensive evidence that numerous biological digestive factors varies between individuals and influence postprandial glycemic response (GR) and insulin response (IR), which are well established risk factors that precipitate the development of Type 2 diabetes mellitus (T2DM). However, no study to date has measured and compared physiological parameters such as mastication, salivary amylase activity, gastric emptying rates and gut microbiota in a multi-ethnic Asian population, with varying prevalence of obesity and T2DM. The aim of this study is to investigate ethnic differences in GR and IR as well as the GI values of foods. Additionally, we aim to examine how physiological digestive factors contribute to inter-ethnic and inter-individual variability in GR and IR. The study outcomes can potentially explain, in part, the varying susceptibility to obesity, T2DM and DM control between Chinese, Malays and Asian-Indians in Singapore, as reflected by the differences in prevalence of obesity, T2DM and DM control among the three local ethnic groups.

Inclusion Criteria:

• Be willing and able to comply with study procedures and given written informed consent
• Chinese/Malay/Indian males, aged 21-40 years old
• Body mass index (BMI) between 18.5 - 24.9 kg/m2
• Fasting blood glucose between 4 - 6 mmol/L
• Sedentary adults, with <1 episode of exercise per week
• Not have a history of food allergies or food intolerances
• Be a non-smoker
• Drinks less than 3 units of alcohol per day
• Not taking antibiotics for the past 3 weeks

Exclusion Criteria:

• Subjects with known chronic diseases, including diabetes, untreated hypertension, renal impairment, gastrointestinal problems, and other significant medical conditions
• BMI <18.5 kg/m2 or >25 kg/m2
• Fasting blood glucose ≥7.0mmol/l
• Alcohol consumption >3 drinks / day
• Use of medications known to affect glucose metabolism
• Recent changes in weight of >5% over the past 3 months
• Significant changes in diet over the past 3 months
• History of eating disorders or irregular eating habits
• Taking antibiotics medications over the past 3 weeks