Effects of Calcium on Gut Functions and Blood Glucose in Humans With Type 2 Diabetes

Summary

The intervention in this study consists of a 75-min intraduodenal infusion of an isotonic solution containing either of calcium chloride (CaCl2) or control (saline). Participants enrolled into the study will receive, in randomised, double-blind fashion (i) Saline (control), (ii) 500 mg CaCl2, or (iii) 1000 mg CaCl2 in three separate sessions, each of which will be separated by at least 4 (and up to 10) days. Each study session will be 4-6 hours. Studies will be carried out in the Clinical Research Facility of the Adelaide Medical School, the University of Adelaide, by staff and students trained in the required techniques.

Eligibility

Inclusion Criteria:

* Males with type 2 diabetes mellitus (T2DM). Diagnosis of T2DM will be based on WHO criteria. Only males will be included to avoid the confounding effects of the menstrual cycle on gastric emptying.
* BMI: 28-38 kg/m².
* HbA1c \>=6.5 - \<=7.9% at screening.
* Blood glucose medications will be required to be withheld for 48 hours prior to each study day.
* Weight-stable (i.e. \<5% fluctuation) at study entry, which will be ascertained by a stable body weight in the preceding 3 months.

Exclusion Criteria:

* Significant GI symptoms, or history of GI disease or surgery
* Current gallbladder or pancreatic disease
* Cardiovascular or respiratory diseases
* Any other illnesses (except type 2 diabetes) as assessed by the investigator - (including chronic illnesses not explicitly listed above)
* Use of prescribed or non-prescribed medications (including vitamins and herbal supplements) which may affect energy metabolism, GI function, bodyweight or appetite (e.g. domperidone, cisapride, anticholinergic drugs (e.g. atropine), metoclopramide, erythromycin, hyoscine, orlistat, green tea extracts, Astragalus, St Johns Wort etc.)
* Lactose intolerance/other food allergy(ies)
* Individuals with low ferritin levels (\<30 ng/mL), or who have donated blood in the 12 weeks prior to taking part in the study
* High performance athletes
* Current intake of \> 2 standard drinks on \> 5 days per week (\>140g/week)
* Current smokers of tobacco (cigarettes, cigars, pipes, sheesha, chewing, vaping etc.)
* Current use of recreational drugs, e.g. marijuana
* Current intake of any illicit substance
* Vegetarians
* Inability to tolerate nasoduodenal tube
* Inability to comprehend study protocol
* HbA1c \<6% or \>7.9%
* Estimated glomerular filtration rate \<45 ml/min
* Any patient whose medication cannot be withheld for 48 hours for medical reasons

Conditions2

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