Regular physical activity (PA) promotes numerous health benefits for people living with type 1 diabetes (T1D). However, PA also complicates blood glucose control. Factors affecting blood glucose fluctuations during PA include activity type, intensity and duration as well as the amount of insulin and food in the body at the time of the activity. To maintain equilibrium with blood glucose concentrations during PA, the rate of glucose appearance (Ra) to disappearance (Rd) in the bloodstream must be balanced. In nondiabetics, there is a rise in glucagon and a reduction in insulin release at the onset of mild to moderate aerobic PA. During intense aerobic -anaerobic work, insulin release first decreases and then rises rapidly in early recovery to offset a more dramatic increase in counterregulatory hormones and metabolites. An “exercise smart” artificial pancreas (AP) must be capable of sensing glucose and perhaps other physiological responses to various types and intensities of PA. The emergence of this new technology may benefit active persons with T1D who are prone to hypo and hyperglycemia.

Background: Exercise causes glycemic disturbances in individuals with type 1 diabetes (T1D). Continuous moderate-intensity aerobic exercise (CON) generally lowers blood glucose (BG) levels and often leads to hypoglycemia. In comparison, circuit-based exercise (CIRC) may attenuate the drop in BG. The goal of this study is to contrast the effects of basal insulin suspension at the onset of two different forms of exercise (CON vs. CIRC). Methods: Twelve individuals (six men and six women) with T1D on insulin pump therapy were recruited for the study. All participants completed a maximal aerobic fitness test and two 40-min exercise sessions, consisting of either continuous treadmill walking or a circuit workout. Basal insulin infusion was stopped at the onset of exercise and resumed in recovery. After providing an initial reference value, volunteers were blinded to their [BG] and were asked to estimate their levels during exercise. Results: Oxygen consumption (47.5 ± 7.5 vs. 54.5 ± 13.5 mL·kg⁻¹·min⁻¹, P = 0.03) and heart rate (122 ± 20 vs. 144 ± 20 bpm, P = 0.003) were lower in CON vs. CIRC. Despite the lower workload, BG levels dropped more with CON vs. CIRC (delta BG = −3.8 ± 1.5 vs. −0.5 ± 3.0 mmol/L for CON vs. CIRC, respectively, P = 0.001). Participants were able to estimate their BG more accurately during CON (r = 0.83) vs. CIRC (r = 0.33) based on a regression analysis. Conclusion: Despite a lower intensity of exercise, with full basal insulin suspension at the start of exercise, CON results in a larger drop in BG vs. CIRC. These findings have implications for single hormone-based artificial pancreas development for exercise. While this study does not negate the importance of frequent capillary BG monitoring during exercise, it does suggest that if persons are knowledgeable about their pre-exercise BG levels, they can accurately perceive the changes in BG during CON, but not during CIRC.

Exercise can improve quality of life in women undergoing chemotherapy for breast cancer, but evidence of the most effective intervention characteristics remains inconclusive. The aim of this study was to determine the effect of exercise on quality of life in women with breast cancer during chemotherapy and examine whether its relationship varies by described exercise modality, dose, and other study characteristics. In this systematic review and meta-analysis, a systematic search of five electronic databases (PubMed, Embase, Web of Science, Cochrane Library, and MEDLINE) from Jan 1, 2005, to May 24, 2025, identified randomised controlled trials evaluating exercise interventions and constructs of quality of life in women undergoing chemotherapy for breast cancer. Standardised mean differences (Hedges' g) were calculated and pooled using three-level random-effects models accounting for dependent effect sizes, and potential moderators were examined. 21 randomised controlled trials (3024 participants) were included. Overall, exercise interventions showed a significant positive effect on constructs of quality of life (ḡ=0·434 [95% CI 0·272-0·595], p<0·0001). Substantial heterogeneity was observed (I²=55·76%). Described exercise modality significantly moderated effects (test statistic 3 for moderator differences 28·85, p<0·0001), with aerobic exercise (ḡ=0·482 [95% CI 0·272-0·595], p<0·0001), combined aerobic-strength training (ḡ=0·397 [0·156-0·639], p=0·0001), and strength-alone (ḡ=0·335 [0·002-0·669], p<0·049) showing significant benefits. This study is retrospectively registered with PROSPERO (CRD420251044479). Exercise interventions significantly affect quality of life in women with breast cancer during chemotherapy. Aerobic and combined aerobic-strength training both showed significant benefits. Further research is needed to establish optimal exercise prescriptions. None.

Athletes with T1D using CSII routinely remove their pump for prolonged periods, predisposing to hyperglycemia and ketosis. We examined the safety and efficacy of an “Untethered” approach - evenly splitting basal insulin between adjusted CSII and a daily injection of insulin degludec. This randomized cross-over study explored glycemic outcomes following in-clinic, fasted exercise (90-minute moderate- and 30-minute high-intensity). After a 1-week run-in, subjects were randomized to Usual CSII or Untethered CSII, for 5-week periods including a week of optimization, and then crossed over. Nineteen patients (age 34 ± 10 (mean ± SD), T1D duration 16 ± 11 years; mean A1C 7.1 ± 0.5) have completed both periods. In the 6 hours following moderate exercise, the Untethered arm showed improved mean glucose and spent 61% more time in range relative to the Usual arm (p<0.001) (Table). Similar trend was seen following high intensity exercise. There were no differences in pre-exercise glucose or total daily insulin dose (TDD). Both regimens were well-tolerated with no serious adverse events. An “Untethered” regimen of injected basal insulin and adjusted-rate CSII is safe and effective in avidly exercising subjects with T1D using CSII and may offer improved glycemic control in the immediate period following moderate-intensity exercise. Disclosure: R. Aronson: Research Support; Self; AstraZeneca, Becton, Dickinson and Company, Boehringer Ingelheim Pharmaceuticals, Inc., Eli Lilly and Company, Janssen Pharmaceuticals, Inc., Medtronic, Merck & Co., Inc., Novo Nordisk Inc., Sanofi, Senseonics. A. Li: None. R.E. Brown: None. S. McGaugh: None. L. Yavelberg: None. M. Riddell: Advisory Panel; Self; Xeris Pharmaceuticals, Inc. Research Support; Self; Dexcom, Inc. Speaker's Bureau; Self; Insulet Corporation, Medtronic MiniMed, Inc. Stock/Shareholder; Self; Zucara Therapeutics Inc. Funding: Novo Nordisk