Study flowchart shows a 32 days plan for oral glucose tolerance (OGTT)-based study and continuous glucose monitoring system (CGMS) study phases.
prediabetes, Diabetes
PREDIABETES, DIABETES
After initial screening, eligible participants were randomized to a premeal almond load treatment-control sequence or to the control-treatment sequence after a run-in period of 2 weeks. Intravenous blood was withdrawn at −30, 0, 30, 60, 90, and 120 min in each period. After completion of the OGTT-based study phase, participants entered the CGMS-based study phase. The CGMS device was inserted in the subcutaneous tissue of the lateral abdominal wall for 3 days. Participants were asked to record activity, mealtime, and premeal almond load timings, which was indicated in Supplementary Fig. Intravenous blood samples were collected at (min): −30, 0, 30, 60, 90, and 120. A crossover of these participants was done and OGTT was repeated in a similar manner. (Fig. Plasma glucose level, serum insulin levels, and serum triglyceride levels were estimated at (min) −30, 0, 30, 60, 90, and 120. C-peptide, plasma glucagon, serum glucagon-like peptide-1 (GLP-1), and plasma dipeptidyl peptidase-4 (DPP-4), levels were assessed at (min) −30, 0, 60, and 120. Assays were done in the following manner: blood glucose and serum triglycerides (enzymatic colorimetric test, Cobas Integra analyzer, Roche Diagnostics GmbH, Mannheim, Germany), serum insulin levels (Chemiluminescence immunoassay, Roche Diagnostics GmbH, Mannheim, Germany), GLP-1 (ELISA assay, Epitope Diagnostics, Inc. San Diego, CA, USA), plasma DPP-4 levels (ELISA assay, Boster Biological Technology, Pleasanton, USA), plasma glucagon (ELISA assay, Sincere Biotech Co. Ltd. Beijing, China), and C-peptide (Electrochemiluminescence immunoassay, Roche Diagnostics GmbH, Mannheim, Germany). In the OGTT-based study phase, participants on the treatment diet were given 20 g of almonds 30 min before drinking 75 g of glucose dissolved in 200 mL of water. While participants on the control diet were not given any food item before OGTT. The nutritional information on almonds is provided in Supplementary Table The continuous glucose monitoring system (CGMS)-based study phase, using CGMS, was a free-living, open-labeled, crossover randomized control trial, where control and premeal almond load diets were compared in 60 participants with prediabetes (The iPro2 CGM device (iPro2 Professional CGM; Medtronic MiniMed, Northridge, CA) is based on the principle of electrochemical detection of blood glucose in subcutaneous interstitial fluid. The CGM sensor was inserted in the subcutaneous tissue of the lateral abdominal wall. The CGMS records and stores 288 glucose readings during a 24-h period as the participants perform the routine daily activities. The sensor was calibrated using finger-prick capillary blood glucose measurements taken at fasting, pre- and post-meals (breakfast, lunch, and dinner) periods by using a glucose meter (Contour Plus One blood glucose meter, Ascensia Diabetes Care Holdings AG, Switzerland). The iPro2 device was worn for 3 complete days. The following day participants returned the iPro2 recorder for upload of the data to a web-based software (CareLink iPro software, MMT-7340, Medtronic MiniMed, Northridge, CA, USA) which provided a summary of the glucose levels over 3 days.Definitions of parameters derived from CGMS are as follows:
The parameters used for glycaemic variability: mean amplitude of glucose excursions (MAGE) (mmol/L), the standard deviation of mean 24-h CGMS blood glucose readings (mmol/L), and mean of daily differences (MoDD).Parameters used for glycaemic control/extent of glycemia: mean 24-h blood glucose reading (M) (mmol/L), time (min) spent in the ideal range (3.9–7.8 mmol/L), AUC ideal range (3.9–7.8 mmol/L) [The above parameters were calculated using the software as mentioned using different formulae (Supplementary file Participants on the control diet consumed a standard diet advised according to guidelines for Asian Indians in India [Dietary composition (% energy) was as follows—control diet: carbohydrates, 50; fat, 35; and protein,15; and treatment diet (with premeal almond load): carbohydrates, 49; fat, 32; and protein, 19. The macronutrient intake of the treatment and control diet has been provided in Supplementary Tables Calculation of sample size: based on previous studies [Randomization: Sequence (premeal almond load treatment followed by standard OGTT or standard OGTT followed by premeal almond load treatment meal) of random numbers were generated by the statistician, not involved in the trial STATA 15.0 statistical software (College Station, Texas, USA). The study Investigator enrolled the participants and assigned participants to the sequence of interventions. This process was followed for both study phases. The trial was stopped after the last follow-up of the last participant enrolled in phase 2 of the study. For every participant, the allocated random number was placed in an opaque envelope. Only the sequence number was mentioned on the cover of the envelope. The envelope was opened at the enrollment for every participant. In these short-term studies, there was no dropout or loss to follow-up. Sixty participants were enrolled in the study and 60 only completed the study.