Of note, participants were encouraged to measure and record their BP twice daily, and if 2 consecutive BP readings were < 110/70 mmHg and/or accompanied by hypotensive episodes with symptoms (dizziness, nausea, headache, and fatigue), they were asked to contact the investigators directly. Antihypertensive medication changes were then made in consultation with cardiologists. In addition, a medication management protocol (ie, doses of antidiabetic medications, including insulin and sulfonylurea) was designed to avoid hypoglycemia. Medication could be reduced in the CER group based on the basal dose at the endocrinologist’s discretion. In the IER group, insulin and sulfonylureas were discontinued on calorie restriction days only, and long-acting insulin was discontinued the night before the IER day. Insulin was not to be resumed until a full day’s caloric intake was achieved.
Measures and analysis. The primary outcomes of this study were changes in BP and weight (measured using an automatic digital sphygmomanometer and an electronic scale), and the secondary outcomes were changes in body composition (assessed by dual-energy x-ray absorptiometry scanning), as well as glycosylated hemoglobin A1c (HbA1c) levels and blood lipids after 6 months. All outcome measures were recorded at baseline and at each monthly visit. Incidence rates of hypoglycemia were based on blood glucose (defined as blood glucose < 70 mg/dL) and/or symptomatic hypoglycemia (symptoms of sweating, paleness, dizziness, and confusion). Two cardiologists who were blind to the patients’ diet condition measured and recorded all pertinent clinical parameters and adjudicated serious adverse events.
Data were compared using independent-samples t-tests or the Mann–Whitney U test for continuous variables, and Pearson’s χ2 test or Fisher’s exact test for categorial variables as appropriate. Repeated-measures ANOVA via a linear mixed model was employed to test the effects of diet, time, and their interaction. In subgroup analyses, differential effects of the intervention on the primary outcomes were evaluated with respect to patients’ level of education, domicile, and sex based on the statistical significance of the interaction term for the subgroup of interest in the multivariate model. Analyses were performed based on completers and on an intention-to-treat principle.
Main results. Among the 205 randomized participants, 118 were women and 87 were men; mean (SD) age was 50.5 (8.8) years; mean (SD) BMI was 28.7 (2.6); mean (SD) SBP was 143 (10) mmHg; and mean (SD) DBP was 91 (9) mmHg. At the end of the 6-month intervention, 173 (84.4%) completed the study (IER group: n = 88; CER group: n = 85). Both groups had similar dropout rates at 6 months (IER group: 14 participants [13.7%]; CER group: 18 participants [17.5%]; P = .83) and were well matched for baseline characteristics except for triglyceride levels.
In the completers analysis, both groups experienced significant reductions in weight (mean [SEM]), but there was no difference between treatment groups (−7.2 [0.6] kg in the IER group vs −7.1 [0.6] kg in the CER group; diet by time P = .72). Similarly, the change in SBP and DBP achieved was statistically significant over time, but there was also no difference between the dietary interventions (−8 [0.7] mmHg in the IER group vs −8 [0.6] mmHg in the CER group, diet by time P = .68; −6 [0.6] mmHg in the IER group vs −6 [0.5] mmHg in the CER group, diet by time P = .53]. Subgroup analyses of the association of the intervention with weight, SBP and DBP by sex, education, and domicile showed no significant between-group differences.