The proposed study is designed to evaluate (i) the effects of saxagliptin, with or without acarbose, on gastric emptying, postprandial glycaemia, and plasma intact GLP-1, insulin, C-peptide and glucagon after a high carbohydrate meal, and (ii) whether the magnitude of the effects of saxagliptin and/or acarbose is related to the rate of gastric emptying, in patients with type 2 diabetes.

Inclusion Criteria:

• Type 2 diabetes (World Health Organisation (WHO) criteria), managed by diet alone (i.e. no oral hypoglycaemic drugs or insulin)
• Body mass index (BMI) 20 - 40 kg/m2
• Age 18 - 70 years
• Males and post-menopausal females (to control for the effect of the menstrual cycle on gut hormone secretion)
• Glycated haemoglobin A1c (HbA1c) ≥ 6.0% and ≤ 7.9%
• Haemoglobin above the lower limit of the normal range (i.e. >135g/L for men and 115g/L for women), and ferritin above the lower limit of normal (i.e. >10mcg/L)

Exclusion Criteria:

• Use of any medication that may influence gastrointestinal motor function, body weight or appetite
• Evidence of drug abuse, consumption of more than 20 g alcohol or 10 cigarettes on a daily basis
• History of gastrointestinal disease, including significant upper or lower gastrointestinal symptoms, pancreatitis, or previous gastrointestinal surgery (other than uncomplicated appendicectomy or cholecystectomy)
• Other significant illness, including epilepsy, cardiovascular or respiratory disease
• Autonomic nerve damage (as assessed by standardised cardiovascular reflex tests [36])
• Impaired renal or liver function (as assessed by calculated creatinine clearance < 90 mL/min or abnormal liver function tests (> 2 times upper limit of normal range))
• Allergy to vildagliptin or any other 'gliptin'
• Donation of blood within the previous 3 months
• Participation in any other research studies within the previous 3 months
• Females who are pre-menopausal
• Inability to give informed consent
• Vegetarians