Isomaltulose improves glycemia and maintains run performance in type 1 diabetes

Journal Title (Medline/Pubmed accepted abbreviation): Med. Sci. Sports Exerc.
Year: 2012
Volume: 144
Number: 5
Page numbers: 800-808
doi: 10.1249/MSS.0b013e31823f6557

Summary of Background and Research Design

Background: People that have type 1 diabetes cannot produce insulin, the hormone that signals the body to take up sugar from the blood stream into cells in the body. In order to control blood sugar, they must inject insulin into their bodies. Exercise, due to its high energy demands, makes it difficult for people with diabetes to estimate how much glucose and insulin are necessary to maintain a healthy level of blood sugar. Incidentally, the “functional capacity” in people with diabetes is typically lower than their counterparts that do not have diabetes. A carbohydrate that is absorbed at a relatively slow rate may allow easier control of blood sugar during endurance exercise in people with type 1 diabetes.

Isomaltulose is a carbohydrate that is absorbed slowly and is used by some persons with diabetes to avoid hyperglycemia (high blood sugar).

Hypothesis: In addition to helping regulate blood sugar, isomaltulose will help people with diabetes perform better during endurance exercise.

Subjects: Men (2) and women (5) with type 1 diabetes, age 34 ± 5 y

Experimental design: randomized, double-blinded, crossover trial

Treatments : 0.6 g/kg body weight mixed with water to a 10% solution
Glucose (also known as dextrose): 41.9 ± 1.2 g
Isomaltulose: 41.8 ± 1.3 g

Protocol : Insulin usage was calculated individually using a clinic-based algorithm.  Subjects injected 1.3 ± 0.2 U of insulin per 10 g of carbohydrates in the evening and at meals.  At a preliminary visit, the participants were first evaluated for VO2peak (also known as VO2max) and peak heart rate on a treadmill.  Then, at least 1 week afterwards, they reported to the laboratory after an overnight fast.  A resting blood sample was acquired, and they filled out questionnaires regarding hunger/fullness.  After a dose of insulin that was 50% their normal dose, they consumed one of the two treatments and then rested for 2 hours.  Blood samples were collected every 30 min.  At t= -15 min before running, resting respiration and heart rate were measured.  For the exercise segment, participants first ran on a motorized treadmill in the pattern- run 4 min, rest 1.5 min- five times with increasing intensities (about 30% VO2peak to 80% VO2peak).  Blood was collected during all rest periods.  They then rested for 5 min and mounted a non-motorized treadmill.  After a 3 min warm up, the participants ran for 10 min; distance, stride frequency, and stride length were noted.  During the last 20 sec, participants reported their perceived level of exertion.  They then rested for 15 min (water allowed), before the last blood sample was collected and hunger/fullness questionnaire was completed.  If hypoglycemia occurred during exercise, participants consumed a solution with 20 g of the same carbohydrate ingested before exercise and their data were not included in the analysis from that point forward.  At least 2 days later, the participants repeated the study with the other treatment.

Summary of Research Findings
  • One participant experienced hypoglycemia during both trials.
  • Blood glucose was greater at every time point after ingestion of dextrose compared to isomaltulose.  The maximum blood glucose concentration measured for dextrose was 10.0 ± 0.5 mM and that for isomaltulose was 5.6 ± 0.6 mM.
  • Blood lactate levels were greater after ingestion of the dextrose beverage at rest, and then were similar throughout the exercise trials.
  • Blood pH became more acidic throughout the whole trial, with no significant differences between variables.
  • At rest, the rate of burning of carbohydrates was greater with isomaltulose than with lipid.  Accordingly, the rate of fat oxidation was greater with dextrose than with isomaltulose.
  • As time increased under the exercise leg, there was an increase in energy coming from carbohydrates and a decrease in energy coming from fat, with a net increase in energy generated.
  • During exercise, there was a similar rate of oxygen consumption regardless of beverage.
  • During the 10 min stint on the non-motorized treadmill, exercise intensity, heart rate, average speed, and distance covered were all similar between trials.
  • Participants felt more full and less hungry after exercise when they had consumed the dextrose beverage compared to the isomaltulose beverage.

Key practice applications

In comparison with dextrose (glucose), isomaltulose helped people with type 1 diabetes avoid hyperglycemia while not compromising their athletic performance.
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