Feasibility and Preliminary Efficacy of Different Intensities of Functional Training in Elderly Type 2 Diabetes Patients with Cognitive Impairment: a Pilot Randomised Controlled Trial

Background: Aging and type-2 diabetes (T2D) are the most important risk factors for cognitive impairment and Alzheimer's disease. Exercise training is an effective, safe, and practical intervention in improving glucose metabolism, physical function, and cognitive disorders. This pilot study investigated the feasibility and preliminary efficacy of high-intensity low-volume (HIFT) vs. low-intensity high-volume (LIFT) functional training in elderly T2D patients with cognitive impairment.

Methods: Forty-eight elderly T2D patients (31 female, 17 male, age 67.5 ± 5.8 years, MMSE score 18.8 ± 2.6, FBG 209.5 ± 37.9) were randomly assigned to HIFT, LIFT and control groups. Cognitive impairment was diagnosed with MMSE ≤ 23 based Iranian society. The SDMT, CVLT-II, BVMT-R, and Stroop tests were used to evaluated processing speed, learning, memory and attention respectively. Physical fitness tests include: tandem stance and walk test; TUG; 6MWT, 10MWT; SSST; 5TSTS; and hand grip was used to evaluated static and dynamic balance, agility, walking endurance, gait speed, lower limb function and lower and upper body strength respectively. As well as, Biochemical (FBG, insulin, HOMA-IR, HbA1c) and physiological outcomes (SBP, and DBP) were assessed. The HIFT group performed six weeks of functional training (three sessions per week) with 120-125% of the lactate threshold. The LIFT group performed six weeks of functional training (five sessions per week) with a 70-75% lactate threshold. Feasibility, safety, and acceptability of exercise programs were assessed at the end of the study.

Result: HIFT showed a higher adherence rate (91% vs. 87.5%), safety, and acceptability compared to LIFT. MMSE and Stroop scores, 6MWT, FBG, insulin, HOMA-IR, HbA1c, SBP, and DBP significantly improved in HIFT (all, P ≤ 0.004) and LIFT (all, P ≤ 0.023). Changes in 6MWT, FBG, insulin, HOMA-IR, and HbA1c in HIFT (all, P ≤ 0.001) and LIFT (all, P ≤ 0.008) were significant compared to the control group. Changes in Stroop scores were significant only in the HIFT group compared to the control group (P = 0.013). SDMT, CVLT-II, BVMT-R, balance test, 10MWT, SSST, TUG and hang grip significantly improved only in HIFT (all, P ≤ 0.038).

Conclusion: HIFT vs. LIFT is a safe, feasible, and effective approach for improving some aspects of physical, biochemical, and cognitive function in elderly T2D patients with cognitive impairment. This pilot study provides initial proof-of-concept data for the design and implementation of an appropriately powered randomised controlled trial (RCT) of HIFT vs. LIFT in a larger sample of elderly T2D patients with cognitive impairment.

Trial Registration: Randomized controlled trial (RCT) (Iranian Registry of Clinical Trials, trial registration number: IRCT20230502058055N1. Date of registration: 11/06/2023.