Differences in the acute effects of aerobic and resistance exercise in subjects with type 2 diabetes: results from the RAED2 Randomized Trial

Abstract

Objective: Both aerobic (AER) and resistance (RES) training, if maintained over a period of several months, reduce HbA1c levels in type 2 diabetes subjects. However, it is still unknown whether the short-term effects of these types of exercise on blood glucose are similar. Our objective was to assess whether there may be a difference in acute blood glucose changes after a single bout of AER or RES exercise.

Study design: Twenty-five patients participating in the RAED2 Study, a RCT comparing AER and RES training in diabetic subjects, were submitted to continuous glucose monitoring during a 60-min exercise session and over the following 47 h. These measurements were performed after 10.9+0.4 weeks of training. Glucose concentration areas under the curve (AUC) during exercise, the subsequent night, and the 24-h period following exercise, as well as the corresponding periods of the non-exercise day, were assessed. Moreover, the low (LBGI) and high (HBGI) blood glucose indices, which summarize the duration and extent of hypoglycaemia or hyperglycaemia, respectively, were measured.

Results: AER and RES training similarly reduced HbA1c. Forty-eight hour glucose AUC was similar in both groups. However, a comparison of glucose AUC during the 60-min exercise period and the corresponding period of the non-exercise day showed that glucose levels were lower during exercise in the AER but not in the RES group (time-by-group interaction p = 0.04). Similar differences were observed in the nocturnal periods (time-by-group interaction p = 0.02). Accordingly, nocturnal LBGI was higher in the exercise day than in the non-exercise day in the AER (p = 0.012) but not in the RES group (p = 0.62).

Conclusions: Although AER and RES training have similar long-term metabolic effects in diabetic subjects, the acute effects of single bouts of these exercise types differ, with a potential increase in late-onset hypoglycaemia risk after AER exercise.

Trial registration: ClinicalTrials.gov NCT01182948.

Conflict of interest statement

Competing Interests: Please note that Enzo Bonora, co-author of the manuscript, is no longer a member of the Editorial Board of the journal. Therefore we do not think it is necessary to make any specific statement on his role. However, we are willing to declare that this does not alter the authors' adherence to all the PLOS ONE policies on sharing data and materials.

Figures

Figure 1. Study flow diagram.

Figure 2. Schematic overview of the study design.

The CGMS sensor was inserted at 8:30–9:30 am. Glucose concentrations were recorded over a 48-h period, starting at 6:30 pm of the same day, corresponding to the beginning of the 60-min exercise session. Several time periods were separately analyzed: the exercise period (6:30–7:30 pm), the subsequent nocturnal period (1:00 am–5:00 am) and the 24-h period following the beginning of the exercise session (exercise day), as well as the corresponding time periods of the following (non-exercise) day. The CGMS was removed at 7:30–8:30 pm of the non-exercise day. Meal times were between 6:30–8:30 am for breakfast, 12:30 am to 2:00 pm for lunch, 3:30–4:30 pm for a snack and 8:00–9:30 pm for dinner.

Figure 3. Mean glucose concentrations behavior during selected periods, in the aerobic (A) and the resistance (B) groups.

Upper panels: glucose concentrations during the 60-min exercise session and the corresponding period of the non-exercise day. Lower panels: glucose concentrations during the nocturnal sleeping period (01:00–05:00 am) of the two days. White circles indicate glucose values in the exercise day, and black circles those in the non-exercise day. P values refer to differences in glucose concentration AUCs between the exercise day and the non-exercise day.