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Study Explores Best Time to Exercise for Patients with Type 1 Diabetes

Aug 13, 2019
Editor: Steve Freed, R.PH., CDE

Author: Marian Ayad, BPharm, PharmD candidate, University of Colorado Skaggs School of Pharmacy and Pharmaceutical Sciences

Is there a difference between morning (in fasting condition) vs. afternoon resistance training exercise for patients with type 1 diabetes?

Building and maintaining muscle mass, strength and metabolism, improving cardiovascular health and bone mineral density, and increasing insulin sensitivity are just some of the benefits of resistance training exercise. But the controversy lies in whether people with diabetes should be engaged in afternoon resistance training or resistance training while in a fasting state in the morning. A previously published study, by Yardley et al., of afternoon resistance exercise for individuals with diabetes, has reported an approximate of 1.5mmoL/L average decline in blood glucose during exercise and an increased risk of nocturnal hypoglycemia. Another study, by Turner et al., where the participants with diabetes performed similar resistance exercise training but while in a fasting state in the morning, has been associated with a mean increase in blood glucose levels of approximately 1.5mmol/L, or no significant change in blood glucose. A thought-provoking recently published study was conducted with the objective of determining the effect of resistance training as morning exercise in a fasting condition vs. afternoon exercise on blood glucose for people with type 1 diabetes. Would these individuals have different glucose response to resistance exercise if performed in the morning while fasting?

The study was a randomized, open-label, cross-over design where 12 participants with type 1 diabetes, without obesity, with no complications present, and recreationally active, were enrolled. Inclusion criteria required the individuals to be between ages 18 and 50, diagnosed with type 1 diabetes for at least a year, HbA1C <9.9% and active (performing both aerobic and resistance exercise). Participants were excluded if they had any condition that would inhibit them from participating in physical activity required for the study, and if they were performing shift work or using any medications, other than insulin, that would affect blood glucose levels. Participants were blinded to continuous glucose monitoring and were provided with a log to record their food intake and insulin dosage (with exercise adjustment doses). They were asked to match the daily food intake and insulin dosage and avoid alcohol and strenuous exercise. In brief, there were two resistance training testing sessions, one at 7 AM (morning exercise in a fasting state, consumed evening meal at least 8 hours prior to session) and the second at 5 PM (afternoon session) that lasted for almost 43 mins and were followed by a 60 minute recovery period in the lab. Blood samples were taken right before exercise and at the end of exercise, and 60 minutes after. There was no significant difference in blood glucose levels at the start of the training sessions between morning and afternoon exercise.

The results reported showed that blood glucose changes were not significant during either the morning or afternoon sessions (effect of time p=0.405); blood glucose levels were higher during exercise and recovery after morning exercise (effect of treatment p=0.041). Morning exercise led to a consistent increase in blood glucose throughout the session (9.5+/-3.0 to 10.4+/-3.0mmol/L) whereas afternoon exercise, during the session, led to an initial decline in blood glucose (8.2+/-2.5 to 7.4+/-2.6mmol/L), with almost a return to baseline during the 60min recovery period. Blood glucose levels were higher at the end of the 60min recovery period after morning exercise compared to afternoon exercise. Complete glucose monitoring showed that mean glucose 6 hours post exercise between the morning and afternoon sessions was not significantly different; mean absolute glucose change for 6 hours post exercise was greater after the morning session compared to the afternoon one, which means there was more glycemic variability after the morning exercise in fasting conditions.

In conclusion, hyperglycemia was found to be more common after the morning exercise session in fasting condition and was higher in the first 6 hours post exercise compared to the afternoon session. In addition to that, there was no significant difference in the overall changes in blood glucose for those 2 sessions. Glucose levels should be monitored closely for individuals with diabetes, especially at the start or change of a new exercise routine, and It might be a good idea for those who suffer from hyperglycemia during and after resistance exercise to consider resistance exercising later in the day as it seems to cause less hyperglycemia.

Practice pearls:

  • Resistance exercising in the morning in a fasting condition for patients with type 1 diabetes can have a different effect on blood glucose levels compared to afternoon resistance training during and after exercise.
  • Hyperglycemia in the morning fasting resistance sessions was more common compared with the afternoon sessions, with the highest levels reported in the first 6 hours following exercise.
  • Closely monitoring blood glucose levels is recommended at the start or change of a new resistance training method.


“The biggest problem most insulin users face is the risk of their blood glucose going too low for up to two days after they exercise. Given that there are no clear recommendations about the best time to exercise with diabetes, a recent study published in …” More: a review of the current information from Dr. Sheri Colberg, Ph.D., FACSM


References for “Study Explores Best Time to Exercise for Patients with Type 1 Diabetes”:

Eshghi SRT, Yardley JE. Morning (fasting) Vs. Afternoon Resistance Exercise in Individuals with Type 1 Diabetes: A Randomized Cross-Over Study. J Clin Endocrinol Metab. 2019 Jun 18. doi: 10.1210/jc.2018-02384.

Yardley JE, Kenny GP, Perkins BA, Riddell MC, Balaa N, Malcolm J, Boulay P,

Khandwala F, Sigal RJ. Resistance versus aerobic exercise: acute effects on glycemia in type 1 diabetes. Diabetes Care. 2013;36(3):537-542.

Turner D, Gray BJ, Luzio S, Dunseath G, Bain SC, Hanley S, Richards A, Rhydderch DC, Ayles M, Kilduff LP, Campbell MD, West DJ, Bracken RM. Similar magnitude of postexercise hyperglycemia despite manipulating resistance exercise intensity in type 1 diabetes individuals. Scand J Med Sci Sports. 2016;26(4):404-412.


Marian Ayad, BSPharm, PharmD candidate, University of Colorado Skaggs School of Pharmacy and Pharmaceutical Sciences