A low-glycemic index meal and bedtime snack prevents postprandial hyperglycemia and associated rises in inflammatory markers, providing protection from early but not late nocturnal hypoglycemia following evening exercise in type 1 diabetes.
OBJECTIVE
To examine the influence of the glycemic index (GI) of foods consumed after evening exercise on postprandial glycemia, metabolic and inflammatory markers, and nocturnal glycemic control in type 1 diabetes.


METHODS
On two evenings (∼1700 h), 10 male patients (27 ± 5 years of age, HbA1c 6.7 ± 0.7% [49.9 ± 8.1 mmol/mol]) were administered a 25% rapid-acting insulin dose with a carbohydrate bolus 60 min before 45 min of treadmill running. At 60 min postexercise, patients were administered a 50% rapid-acting insulin dose with one of two isoenergetic meals (1.0 g carbohdyrate/kg body mass [BM]) matched for macronutrient content but of either low GI (LGI) or high GI (HGI). At 180 min postmeal, the LGI group ingested an LGI snack and the HGI group an HGI snack (0.4 g carbohdyrate/kg BM) before returning home (∼2300 h). Interval samples were analyzed for blood glucose and lactate; plasma glucagon, epinephrine, interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α); and serum insulin, cortisol, nonesterified fatty acid, and β-hydroxybutyrate concentrations. Interstitial glucose was recorded for 20 h postlaboratory attendance through continuous glucose monitoring.


RESULTS
Following the postexercise meal, an HGI snack induced hyperglycemia in all patients (mean ± SD glucose 13.5 ± 3.3 mmol/L) and marked increases in TNF-α and IL-6, whereas relative euglycemia was maintained with an LGI snack (7.7 ± 2.5 mmol/L, P < 0.001) without inflammatory cytokine elevation. Both meal types protected all patients from early hypoglycemia. Overnight glycemia was comparable, with a similar incidence of nocturnal hypoglycemia (n = 5 for both HGI and LGI).


CONCLUSIONS
Consuming LGI food with a reduced rapid-acting insulin dose following evening exercise prevents postprandial hyperglycemia and inflammation and provides hypoglycemia protection for ∼8 h postexercise; however, the risk of late nocturnal hypoglycemia remains.
Faculty of Health and Life Sciences, Northumbria University, Newcastle-upon-Tyne, U.K.
Matthew D
MD
Campbell
Institute of Cellular Medicine, Newcastle University, Newcastle-upon-Tyne, U.K.
Mark
M
Walker
Institute of Cellular Medicine, Newcastle University, Newcastle-upon-Tyne, U.K.
Michael I
MI
Trenell
Faculty of Health and Life Sciences, Northumbria University, Newcastle-upon-Tyne, U.K.
Emma J
EJ
Stevenson
Applied Sports, Technology, Exercise and Medicine Research Centre, College of Engineering, Swansea University, Swansea, U.K.
Daniel
D
Turner
Applied Sports, Technology, Exercise and Medicine Research Centre, College of Engineering, Swansea University, Swansea, U.K.
Richard M
RM
Bracken
Institute of Cellular Medicine, Newcastle University, Newcastle-upon-Tyne, U.K.
James A
JA
Shaw
Faculty of Health and Life Sciences, Northumbria University, Newcastle-upon-Tyne, U.K. d.j.west@northumbria.ac.uk.
Daniel J
DJ
West
D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D003922:Diabetes Mellitus, Type 1 / Q000503:physiopathology*; D004040:Dietary Carbohydrates / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D038321:Glycemic Index; D006801:Humans; D006943:Hyperglycemia / Q000517:prevention & control; D007003:Hypoglycemia / Q000517:prevention & control; D061266:Insulin, Short-Acting / Q000008:administration & dosage*; D008297:Male; D062407:Meals; D019518:Postprandial Period; D012420:Running / Q000502:physiology; D062410:Snacks; D013997:Time Factors; D055815:Young Adult
D001786:Blood Glucose; D004040:Dietary Carbohydrates; D061266:Insulin, Short-Acting