⏪ Rewind: Improving beta-cell function in type 2 diabetes: Exercise is key Original paper

In this randomized controlled trial, combining exercise with caloric restriction was more effective than caloric restriction alone for improving beta-cell function in participants with type 2 diabetes.

This Study Summary was published on February 12, 2024.

Quick Summary

In this randomized controlled trial, combining exercise with caloric restriction was more effective than caloric restriction alone for improving beta-cell function in participants with type 2 diabetes.

What was studied?

Whether exercise enhances the effects of diet-induced weight loss on beta-cell function.

The primary outcome was the change in late-phase disposition index (the product of insulin sensitivity and insulin secretion during the final 30 minutes of the hyperglycemic clamp technique, which involves intravenous infusion of glucose to elevate blood glucose levels).

The secondary outcomes were measures of beta-cell function during a 3-hour oral mixed-meal tolerance test, including disposition index (calculated as the product of insulin sensitivity and insulin secretion rate, as assessed over 120 minutes).

Who was studied?

82 adults (average age of 58; 65% men, 35% women) with newly diagnosed (<7 years) type 2 diabetes and overweight or obesity.

How was it studied?

In this 16-week randomized controlled trial, the participants were assigned to 1 of 4 groups:

  • Control: no intervention (standard care)
  • Dietary control (DCON): individualized dietary recommendations to facilitate an energy deficit of 25%–30% per day and a macronutrient distribution of 45%–60% of energy from carbohydrate, 15%–20% from protein, and 20%–35% from fat (<7% of total energy from saturated fat)
  • Medium exercise dose (MED): dietary control intervention + 2 aerobic exercise sessions (30 minutes at a target intensity of 60%–100% of maximal heart rate) and 1 combined aerobic and resistance exercise session per week (150–160 minutes total)
  • High exercise dose (HED): dietary control intervention + 4 aerobic exercise sessions and 2 combined aerobic and resistance exercise sessions per week (300–330 minutes total)

What were the results?

Compared to the control group, the late-phase disposition index improved (increased) in all of the intervention groups. There was evidence of a dose-response relationship, with the greatest improvements observed in HED. The improvements were mainly driven by an increase in insulin sensitivity, as opposed to insulin secretion rate, which did not differ between the intervention groups.

Compared to the control, the disposition index derived from the mixed meal tolerance test also improved in all of the intervention groups. The improvement was greater in HED and MED than in DCON. Again, this change was driven by an improvement in insulin sensitivity; there were no differences between any of the groups for insulin secretion rate.

Anything else I need to know?

Body weight decreased by 0%, 7%, 10%, and 12% from baseline in the control, DCON, MED, and HED groups, respectively. Based on a mediation analysis by the investigators, exercise seemed to improve insulin sensitivity largely independent of its effects on weight loss, whereas improvements in insulin sensitivity from caloric restriction seemed to be almost completely driven by weight loss.

This Study Summary was published on February 12, 2024.