Aerobic Exercise for Type 1 Diabetes

Age: 18 - 65

Sex: Female

Trial Phase: Academic

Sponsor: University of Alberta

Must be taking: Oral contraceptives

Must not be taking: Glucose affecting medications

Disqualifiers: Cardiovascular disease, Neuropathy, Retinopathy, others

No Placebo Group All trial participants will receive the active study treatment (no placebo)

Compensation: Varies

Number of Visits: 4

15 Participants Needed

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial aims to understand how aerobic exercise affects blood sugar levels in women with type 1 diabetes who use birth control pills. Participants will wear a device to track glucose levels during different phases of their menstrual cycle and perform a 45-minute cycling workout. The trial is suitable for women diagnosed with type 1 diabetes for at least a year, who have regular periods, use birth control pills, and live in Edmonton, Alberta. As an unphased trial, it offers participants the chance to contribute to valuable research that could enhance diabetes management for women.

Will I have to stop taking my current medications?

The trial requires that you do not use medications (other than insulin) that would affect blood glucose levels. If you are taking such medications, you may need to stop them to participate.

What prior data suggests that aerobic exercise is safe for females with type 1 diabetes?

Research has shown that regular aerobic exercise is generally safe and offers many health benefits for people with type 1 diabetes. Studies indicate that moderate exercise, such as 45-minute sessions at 60% of maximum aerobic capacity, can lower blood sugar levels from about 155 mg/dL to 110 mg/dL. This decrease occurs whether the exercise is done during the follicular phase or the luteal phase of the menstrual cycle.

Exercise affects blood sugar levels differently depending on the menstrual phase. During the luteal phase, higher blood sugar levels might help prevent low blood sugar (hypoglycemia) after exercise. However, during the follicular phase, there is a higher chance of experiencing high blood sugar (hyperglycemia) 24 hours after exercising.

Overall, these findings suggest that the exercise in this study is well-tolerated and has predictable effects on blood sugar, making it safe for participants with type 1 diabetes. ^{1 2 3 4 5}

Why are researchers excited about this trial?

Researchers are excited about aerobic exercise as a treatment for Type 1 Diabetes because it offers a natural and holistic approach that differs from the traditional reliance on insulin and glucose-monitoring technologies. Unlike conventional treatments that focus primarily on blood sugar regulation through medication, aerobic exercise can enhance overall metabolic health and improve insulin sensitivity without additional drugs. By examining the effects of exercise during different phases of the menstrual cycle (follicular and luteal), this approach could provide personalized insights into how exercise timing might optimize glucose control for women with Type 1 Diabetes, potentially leading to more tailored and effective management strategies.

What evidence suggests that aerobic exercise could be effective for type 1 diabetes?

Research has shown that aerobic exercise can help control blood sugar levels in people with type 1 diabetes. One study found that blood sugar levels dropped from about 155 mg/dL to 110 mg/dL after moderate aerobic exercise, regardless of the menstrual phase. This indicates that exercise can effectively manage blood sugar. During the luteal phase (the second half of the menstrual cycle), slight differences in blood sugar response to exercise occurred, but exercise remained beneficial overall. In summary, aerobic exercise is a promising way to manage diabetes, even with the natural changes of the menstrual cycle. ^{1 2 3 4 6}

Are You a Good Fit for This Trial?

This trial is for women with type 1 diabetes who've had it for at least a year, live in Edmonton, have regular menstrual cycles, and use monophasic oral contraceptives. It's not for those with heart disease, severe nerve damage, recent insulin changes, high blood pressure, certain eye conditions, or on medications affecting blood sugar.

Inclusion Criteria

I have been diagnosed with Type 1 diabetes for over a year.

I am using monophasic birth control pills.

Residing in Edmonton, Alberta and able to visit the lab at the University of Alberta

Exclusion Criteria

I have not changed my insulin plan in the last two months.

I have an active eye condition where new blood vessels are growing abnormally.

I have severe nerve pain or numbness in my hands or feet.

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

1-2 weeks

1 visit (in-person)

Pre-test Measures

Participants undergo pre-test measures including questions about menstrual cycle, physical activity, medication, blood pressure, anthropometric measurements, blood sample for HbA1c, and an incremental treadmill test to determine aerobic capacity.

1 day

1 visit (in-person)

Testing Sessions

Participants perform two testing sessions with aerobic exercise and continuous glucose monitoring, separated by at least 5 days. Sessions occur during different phases of the menstrual cycle.

2 weeks

2 visits (in-person)

Follow-up

Participants are monitored for changes in blood glucose and other secondary outcomes post-exercise.

1 week

What Are the Treatments Tested in This Trial?

Interventions

• Follicular Phase Aerobic Exercise
• Luteal Phase Aerobic Exercise

Trial Overview

The study tests how aerobic exercise affects glucose levels during different phases of the menstrual cycle in women with type 1 diabetes. Participants will do a monitored exercise session and wear a continuous glucose monitor during the last week of active pills and no pill/placebo phase.

How Is the Trial Designed?

Group I: All participants Experimental Treatment 2 Interventions

All participants will be in a single study arm.

Who Is Running the Clinical Trial?

University of Alberta

Lead Sponsor

Trials

957

Recruited

437,000+

Women and Children's Health Research Institute, Canada

Collaborator

Trials

18

Recruited

24,800+

Published Research Related to This Trial

In a study of 35 women (11 sedentary and 24 moderately exercising), 48% of the exercising women experienced luteal phase deficiency (LPD), and only 45% had ovulatory cycles, compared to 90% ovulation in sedentary women.

The exercising women with LPD had significantly longer follicular phases and shorter luteal phases, along with lower levels of key hormones like pregnanediol-3-glucuronide (PdG), suggesting that exercise may disrupt normal menstrual cycle function and hormone regulation.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

High frequency of luteal phase deficiency and anovulation in recreational women runners: blunted elevation in follicle-stimulating hormone observed during luteal-follicular transition. De Souza, MJ., Miller, BE., Loucks, AB., et al.[2022]

In a study involving different nutritional states and exercise, metabolic and hormonal responses to exercise were generally similar between the follicular and luteal phases of the menstrual cycle, indicating consistent physiological responses regardless of the phase.

However, in the luteal phase, free fatty acid responses were lower and insulin and growth hormone levels were elevated in fasted subjects, suggesting that hormonal fluctuations during this phase can influence metabolic responses to exercise.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Effects of menstrual cycle on metabolic responses to exercise. Bonen, A., Haynes, FJ., Watson-Wright, W., et al.[2018]

In a study of nine healthy females, exercise was found to significantly increase levels of estradiol and progesterone during the luteal phase of the menstrual cycle, indicating that exercise acts as a physiological stimulus for these hormones.

Follicle-stimulating hormone (FSH) levels increased during exercise in the follicular phase but not in the luteal phase, while luteinizing hormone (LH) levels remained unchanged, suggesting that the hormonal response to exercise varies depending on the phase of the menstrual cycle.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Ovarian hormonal responses to exercise. Jurkowski, JE., Jones, NL., Walker, C., et al.[2017]

Luteal phase defects (LPD) are common in physically active women and athletes, with a prevalence of 48% and an incidence rate of 79% for anovulatory cycles, indicating a significant impact on menstrual health.

LPD is associated with metabolic changes resembling a hypometabolic state, including lower levels of key hormones like T3, leptin, and insulin, but does not appear to reduce bone mineral density if estradiol levels are adequate.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Menstrual disturbances in athletes: a focus on luteal phase defects. De Souza, MJ.[2018]

In a pilot study of 5 women with type 1 diabetes, non-insulin-mediated glucose disposal was significantly higher during the luteal phase compared to the follicular phase, suggesting changes in glucose metabolism throughout the menstrual cycle.

While the overall insulin sensitivity did not show significant differences between the two phases, three out of five participants experienced a decline in insulin sensitivity during the luteal phase, indicating that some women may need to adjust their insulin dosages based on their menstrual cycle.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Menstrual cycle effects on insulin sensitivity in women with type 1 diabetes: a pilot study. Trout, KK., Rickels, MR., Schutta, MH., et al.[2016]

Exercising women with luteal phase deficient (LPD) menstrual cycles show hormonal changes indicative of a hypometabolic state, similar to those seen in amenorrheic athletes, suggesting a metabolic adaptation to energy deficiency.

Total T3 and leptin levels were significantly lower in exercising women with LPD compared to sedentary women with ovulatory cycles, indicating that hormonal alterations may be linked to energy balance and metabolic health.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Luteal phase deficiency in recreational runners: evidence for a hypometabolic state. De Souza, MJ., Van Heest, J., Demers, LM., et al.[2015]

The study involving eight eumenorrheic women found that the menstrual cycle phase affects insulin levels at rest, with higher insulin levels observed in the luteal phase compared to the follicular phase before exercise.

Despite the differences in insulin levels at rest, the menstrual cycle phase did not significantly impact glucose responses during sub-maximal exercise, suggesting that exercise may override the effects of hormonal changes on glucose metabolism.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

EFFECT OF MENSTRUAL CYCLE PHASE ON THE GLUCOSE-INSULIN RELATIONSHIP AT REST AND DURING EXERCISE. Hackney, AC., Cyren, CH., Brammeier, M., et al.[2022]

Aerobic exercise performance is significantly impaired during the midluteal (ML) phase of the menstrual cycle compared to the midfollicular (MF) phase, as evidenced by lower mean power output and slower cycling times in a study of 12 recreationally active women.

Increased levels of progesterone during the ML phase were associated with greater pre-exercise mood disturbance and higher fatigue ratings during the exercise, although heart rate and oxygen uptake remained consistent across both phases.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Exercise Performance Is Impaired during the Midluteal Phase of the Menstrual Cycle. Freemas, JA., Baranauskas, MN., Constantini, K., et al.[2023]

In a study involving seven healthy women, the infusion of high levels of glucose during exercise eliminated the expected metabolic differences caused by hormonal fluctuations throughout the menstrual cycle.

While estrogen and progesterone levels were significantly higher during the luteal phase compared to the follicular phase, these hormonal changes did not affect substrate utilization during exercise when glucose was infused.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

The effect of the menstrual cycle and hyperglycaemia on hormonal and metabolic responses during exercise. Hulton, AT., Malone, JJ., Campbell, IT., et al.[2022]

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A decline in blood glucose levels was observed after exercise, regardless of menstrual phase, from approximately 155 mg/dL to about 110 mg/dL.

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Yardley said. Level 1 hyperglycemia 24 hours after exercise was significantly more frequent in the follicular phase, compared with the luteal ...