University of Maryland: Hypoglycemia Associated Autonomic Failure in Type 1 Diabetes Mellitus

Jun 28, 2019


Although exercise is one of the best forms of diabetes management, many type 1 diabetics do not exercise due to the fear of becoming hypoglycemic (having low blood sugar). This study demonstrated that Autonomic nervous system (ANS) counterregulatory failure plays an important role in exercise associated hypoglycemia in Type 1 diabetes mellitus. In T1D, ANS responses are significantly reduced and are even more reduced by prior episodes of hypoglycemia. There is also a large sexual dimorphism of reduced ANS responses during submaximal exercise in both Type 1 DM patients as well as healthy individuals, which is unexplained. Current accumulating data are demonstrating that that serotonergic pathways can regulate ANS discharge. The purpose of this study was to determine whether or not SSRI fluoxetine (Prozac) can improve SNS responses during exercise.


At the University of Maryland, researchers are conducting a double blind study of the effects of SSRI medication fluoxetine (Prozac) on the Autonomic nervous system (ANS) for people with type 1 diabetes during exercise. The motivation behind this study is the prominence of fear from many type 1 diabetics to exercise and induce hypoglycemia (low blood sugar). Coincidentally, reduced ANS responses produce sexual dimorphism during exercise in both type 1 diabetics and healthy adults. Per this “coincidence”, researchers wonder if pathways that deal with serotonin flow and activity may regulate ANS production. Since fluoxetine is a selective serotonin reuptake inhibitor (SSRI) and increases serotonin flow, it is plausible that its use could reduce ANS responses during exercise.


Study Information

This study is classified as interventional (participants receive treatment, referred to as “interventions”), randomized (participants are chosen by chance for treatment), and double blind (neither the participant nor the investigator knows the identity of the variable, i.e. who is given treatment). It consists of two trials: Trial 1 as ‘Active Comparator’ with an SSRI; and Trial 2 as Placebo Comparator without administration of SSRI. A seemingly simple study of these two trials attempts to conclude whether SSRI medication may reduce ANS occurrences during exercise and the fear of hypoglycemia.


Inclusion Criteria

Sixty-hour participants will be researched in this study (thirty-two healthy adults between ages of 18-45, thirty-two type 1 diabetic patients between ages of 18-45). In each of the two groups of 32 individuals, there will be 16 male and 16 female. The range of HbA1c for participants should be between 6 and 10 percent. To be included in the group of type 1 diabetics, each must have received and prove an official diagnosis of type 1 diabetes. While type 1 diabetics, the participants cannot have clinical diagnosis of diabetic tissue complications retinopathy, neuropathy, stasis ulcers, and more. For all participants their body mass index (BMI) must be less than 40 kilograms.


Exclusion Criteria

While it is not difficult to meet the inclusion criteria to be a patient in the study, the exclusion criteria is more extensive. It includes pregnant women, people who cannot give voluntary consent, have a history of hypertension, heart disease, or cerebrovascular incidents, have anemia or bleeding diathesis, those with recent mental illness (what qualifies as “recent” is not stated), and smokers. Additionally, to not interfere with results from fluoxetine treatment, people who take certain medications including anticoagulants, non-selective beta blockers, sedatives/hypnotics, anticonvulsants, antipsychotics, antidepressants, mood stabilizers, and antiparkinsonian drugs are excluded.



The University of Maryland is the primary sponsor of this study, with assistance from others. The National, Heart, Lung, and Blood (NHLB) Institute also contributes to the research and work performed. The main researcher attributed to the study is Stephen N. Davis, MBBS, of the University of Maryland.

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