Interstitial glucose concentrations and hypoglycemia during 2 days of caloric deficit and sustained exercise: a double-blind, placebo-controlled trial.
Military personnel and some athlete populations endure short-term energy deficits from reduced energy intake and/or increased energy expenditure (EE) that may degrade physical and cognitive performance due to severe hypoglycemia (<3.1 mmol/l). The extent to which energy deficits alter normoglycemia (3.9-7.8 mmol/l) in healthy individuals is not known, since prior studies measured glucose infrequently, not continuously. The purpose of this study was to characterize the glycemic response to acute, severe energy deficit compared with fully fed control condition, using continuous glucose monitoring (CGM). For 2 days during a double-blind, placebo-controlled, crossover study, 23 volunteers (17 men/6 women; age: 21.3 ± 3.0 yr; body mass index: 25 ± 3 kg/m) increased habitual daily EE [2,300 ± 450 kcal/day [means ± SD)] by 1,647 ± 345 kcal/day through prescribed exercise (~3 h/day; 40-65% peak O2consumption), and consumed diets designed to maintain energy balance (FED) or induce 93% energy deficit (DEF). Interstitial glucose concentrations were measured continuously by CGM (Medtronic Minimed). Interstitial glucose concentrations were 1.0 ± 0.9 mmol/l lower during DEF vs. FED (P < 0.0001). The percentage of time spent in mild (3.1-3.8 mmol/l) hypoglycemia was higher during DEF compared with FED [mean difference = 20.5%; 95% confidence interval (CI): 13.1%, 27.9%; P = 0.04], while time spent in severe (<3.1 mmol/l) hypoglycemia was not different between interventions (mean difference = 4.6%; 95% CI: -0.6%, 9.8%; P = 0.10). Three of 23 participants spontaneously reported symptoms (e.g., nausea) potentially related to hypoglycemia during DEF, and an additional participant reported symptoms during both interventions. These findings suggest that severe hypoglycemia rarely occurs in healthy individuals enduring severe, short-term energy deficit secondary to heavy exercise and inadequate energy intake.
Military Nutrition Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts Tracey.smith10.civ@mail.mil.
Tracey J
TJ
Smith
Military Nutrition Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts.
Marques A
MA
Wilson
Military Nutrition Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts.
J Philip
JP
Karl
Military Nutrition Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts.
Krista
K
Austin
Military Nutrition Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts.
Asma
A
Bukhari
Military Nutrition Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts.
Stefan M
SM
Pasiakos
Military Nutrition Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts.
Kristie L
KL
O'Connor
Military Nutrition Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts.
Harris R
HR
Lieberman
D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D015992:Body Mass Index; D018592:Cross-Over Studies; D004032:Diet / Q000379:methods; D004311:Double-Blind Method; D002149:Energy Intake / Q000502:physiology*; D004734:Energy Metabolism / Q000502:physiology; D015444:Exercise / Q000502:physiology*; D005260:Female; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D007003:Hypoglycemia / Q000378:metabolism*; D008297:Male; D055815:Young Adult
D001786:Blood Glucose; D005947:Glucose
caloric restriction; continuous glucose measurement; energy deficit; glycemia; interstitial glucose