2.8.3. Study Variables
T2DM
CHRONIC DISEASES
The clinical variables of the study were obtained through a systematic anamnesis. The following variables were included: age, sex, body mass index, insulin usage, profession, education, presence of chronic diseases, shift work status, duration since T2DM diagnosis, medications in use, use or not of insulin, use or not of sleep-inducing medications, family history of T2DM, abdominal and cervical circumference and blood pressure. HbA1C was obtained from all the patients. We limited our sample to patients with glycohemoglobin between 7 and 10%. In fact, greater glycemic variability is found in patients with a higher HbA1C value. Therefore, we did not include those with glycohemoglobin <7%. However, in order to ensure homogeneity of glycemic variability between the patients, we limited the maximum value of HbA1C to enter the study to 10%. We subsequently evaluated whether the patients who were randomized to the intervention in the melatonin (3 mg)–washout–placebo order had mean HbA1C values different from those who were randomized to the placebo–washout–melatonin (3 mg) order.Creation of study variablesMain objectiveA general variable (GV) was obtained by averaging the sum of the difference in blood glucose after breakfast (AB) and before breakfast (BB), after lunch (AL) and before lunch (BL), after dinner (AD) and before dinner (BD), on the last three days of the placebo and melatonin use in the study (Day 5, Day 6 and Day 7) and dividing this result by 3 [We obtained two different variables: the real difference, considering both negative and positive values, and another considering only positive values in the calculation (delta or amplitude).Specific objectivesWe analyzed separately the mean of the differences between the placebo and melatonin at breakfast, lunch and dinner on the last three days of the study.We also created the same variables (general and specific) considering only the seventh day. The general variable was obtained as follows:The specific variable on Day 7 was obtained as follows:In addition, we calculated the mean glycemic variability coefficient for each patient when using the placebo and melatonin. The glycemic variability coefficient was calculated by dividing the standard deviation by the mean.Finally, we calculated the difference between the post-dinner glycemia of Day 6 and the pre-breakfast glycemia of Day 7. In this case, we also calculated the delta and the real difference. This variable was obtained as follows:We used the STOP-Bang [