Acute effect of the renally excreted low-calorie sweetener, acesulfame potassium (Ace-K), on urinary glucose excretion in healthy humans.

Following enrolment, healthy participants will be studied on 2 occasions, separated by at least 3 days, in a double-blinded, randomised, crossover design. On the evening preceding the study day (~1900h), participants will be given a standardised evening meal (McCain beef Lasagne 400g, 2529 kJ with 66% carbohydrate, 17% protein and 17% fat). Following this meal, participants will be asked to fast from solids and liquids (other than water) until the following morning, when they will attend the Clinical Research Facility of the Adelaide Health and Medical Science building at ~0800h. On each study day, an intravenous cannula will be placed into a vein of each forearm for IV dextrose infusion and blood sampling, respectively. A hyperglycaemic clamp will be maintained at 10 mmol/L from t = 0 to 210 min, by intravenous administration of 25% dextrose. Following an initial 30 min of stabilisation of the hyperglycaemic clamp, participants will be asked to empty their bladder at t = 30 min. Subsequently, participants will consume 250 mL water together with 5 gelatin capsules containing a total dose of (i) 900 mg Ace-K (calculated based on acceptable daily intake at 60 kg of body weight), or (ii) 900 mg cellulose (placebo) at t = 30 min and 250 mL water every 30 min between t = 60 to 180 min respectively, each within 5 min. In both groups, urine samples will be collected every 60 min between t = 30-210 min. The glucose levels in the urine will be measured immediately using a Yellow Springs Instruments (YSI) 2900 analyser. “Arterialised” venous blood will be sampled every 30 min, kept warm with a heating pad, between t = 0 and 210 min for measurement of plasma insulin. Serum creatinine will be measured and used for calculating the estimated Glomerular Filtration Rate (eGFR) by the CKD-EPI formula. Renal artery blood flow will be measured using ultrasound at t = 30 and 210 min. After a final blood sample is collected, participants will be served a light lunch (a sandwich ordered from a Cafe within the building, approximately 350 kcal with 60% carbohydrate, 20% protein and 20% fat; a yoghurt, ~140 kcal with 60% carbohydrate, 30% protein and 10% fat) with water and once the blood concentration has stabilised above 4 mmol/L for 30 min, they will be free to leave the laboratory.