Discover how isomaltulose, a slow-release sugar, stabilizes blood glucose during and after exercise for individuals with Type 1 Diabetes.
For individuals with Type 1 Diabetes (T1DM), exercise is a double-edged sword. While essential for health, physical activity can trigger dangerous drops in blood sugar, a condition known as hypoglycemia. For decades, the standard advice has been to consume carbohydrates (CHO) before workouts to prevent this. However, emerging research reveals that not all carbohydrates are created equal, and a slow-release sugar called isomaltulose is proving to be a superior tool for stabilizing blood glucose during and after exercise.
Managing Type 1 Diabetes is a constant balancing act of insulin, food, and activity. During exercise, the body's demand for energy surges, leading to an increased uptake of glucose from the blood. At the same time, insulin action is heightened. This combination can cause blood sugar levels to plummet, leading to hypoglycemia, which can be immediate or occur hours after the workout has ended 1 8 .
The traditional solution—consuming fast-acting carbohydrates like dextrose or sucrose before exercise—often creates a metabolic rollercoaster. These high-glycemic index (GI) sugars cause a rapid spike in blood glucose, followed by a sharp crash, sometimes exacerbated by the exercise itself. This unstable response makes glycemic control challenging and deters many with T1DM from leading an active life.
The core of this problem lies in the Glycemic Index (GI), a measure of how quickly a carbohydrate raises blood sugar levels.
(like dextrose): Rapidly digested, causing a sharp, high peak in blood glucose.
Hypoglycemia (low blood sugar) during or after exercise is one of the most common barriers to physical activity for people with Type 1 Diabetes.
Isomaltulose, also known by the trade name Palatinose™, is a carbohydrate that is changing the game for diabetic athletes. It is a disaccharide composed of glucose and fructose, naturally found in honey and sugarcane but produced commercially from sucrose 5 7 .
Its unique power lies in its chemical structure. While sucrose has a relatively weak alpha-1,2 glycosidic bond, isomaltulose has a stronger alpha-1,6 glycosidic bond 5 . This simple structural difference makes isomaltulose resistant to rapid digestion in the small intestine. It is hydrolyzed into glucose and fructose at a rate only 20-25% that of sucrose 8 . This results in a low GI of 32, compared to 96 for dextrose, providing full carbohydrate energy (4 kcal/g) in a slow, steady stream 1 .
Isomaltulose has a stronger alpha-1,6 glycosidic bond compared to sucrose's alpha-1,2 bond, making it more resistant to rapid digestion.
Isomaltulose is hydrolyzed at only 20-25% the rate of sucrose, leading to a gradual release of glucose into the bloodstream.
A pivotal 2001 randomized controlled trial published in Medicine & Science in Sports & Exercise directly investigated the effects of isomaltulose versus dextrose on post-exercise glycemia in individuals with T1DM 1 8 .
The study was designed as a crossover trial, meaning each participant acted as their own control, enhancing the reliability of the results 1 8 .
Eight adults with T1DM who were regularly active.
On two separate occasions, participants consumed 75 grams of either isomaltulose (ISO) or dextrose (DEX) in a 10% solution.
Participants administered a reduced dose (75% less) of their rapid-acting insulin immediately before drinking the test solution.
Two hours after consuming the drink, participants performed 45 minutes of treadmill running at a high intensity (80% of their peak oxygen uptake).
Blood glucose (BG) was measured for 2 hours before and 3 hours after exercise. Cardiorespiratory parameters were collected to calculate fuel oxidation rates.
| Aspect | Isomaltulose (ISO) Trial | Dextrose (DEX) Trial |
|---|---|---|
| Carbohydrate Consumed | 75 g Isomaltulose (GI=32) | 75 g Dextrose (GI=96) |
| Insulin Dose | Reduced by 75% | Reduced by 75% |
| Pre-Exercise Period | 2 hours of rest | 2 hours of rest |
| Exercise Task | 45-min treadmill run at 80% VO₂peak | 45-min treadmill run at 80% VO₂peak |
| Post-Exercise Monitoring | 3 hours | 3 hours |
The findings were striking and demonstrated a clear metabolic advantage for isomaltulose.
Under the isomaltulose condition, carbohydrate oxidation was lower, and lipid (fat) oxidation was higher 1 .
| Parameter | Isomaltulose (ISO) | Dextrose (DEX) | Significance |
|---|---|---|---|
| Pre-Exercise BG Peak (Δ mmol/L) | +4.5 ± 0.4 | +9.1 ± 0.6 | P < 0.01 |
| CHO Oxidation (final 10 min of exercise, g/min) | 2.85 ± 0.07 | 3.18 ± 0.08 | P < 0.05 |
| Lipid Oxidation (final 10 min of exercise, g/min) | 0.33 ± 0.03 | 0.20 ± 0.03 | P < 0.05 |
| Post-Exercise BG AUC | 21% lower | - | P < 0.05 |
| Mean Post-Exercise BG (mmol/L) | 3.0 mmol/L lower | - | P < 0.05 |
The improved glycemic control stems from a fundamental shift in energy metabolism, driven by isomaltulose's slow release.
By providing a slow and steady stream of glucose, isomaltulose avoids the large insulin spike that typically follows high-GI carbohydrate intake. Stable insulin levels during exercise are crucial for preventing hypoglycemia.
The lower insulin response and prolonged energy release from isomaltulose allow the body to increase its reliance on fat as a fuel source during endurance exercise. This "spares" carbohydrates—both the glucose in the blood and the glycogen stored in muscles and the liver. With more CHO in reserve at the end of exercise, the body is less likely to experience a dangerous glucose drop in the critical hours of recovery 1 3 .
Click the buttons below to see how blood glucose levels differ between isomaltulose and dextrose:
| Tool / Reagent | Function in the Experiment |
|---|---|
| Isomaltulose (Palatinose™) | The investigational low-glycemic index (GI=32) carbohydrate. Its slow digestion is the key variable being tested. |
| Dextrose | The high-glycemic index (GI=96) control carbohydrate. Serves as the benchmark against which isomaltulose is compared. |
| Treadmill | Standardized equipment for administering the controlled exercise stimulus at a specific intensity (80% VO₂peak). |
| Blood Glucose Analyzer | For frequent measurement of blood glucose levels before, during, and after exercise to track glycemic response. |
| Indirect Calorimetry System | A device that measures oxygen consumption and carbon dioxide production. Used to calculate rates of carbohydrate and fat oxidation in real-time during exercise. |
| Rapid-Acting Insulin Analog | (e.g., Insulin Aspart/Lispro). Administered by participants in a reduced dose to mimic real-world diabetes management during the experiment. |
The benefits of isomaltulose extend beyond T1DM. A 2025 meta-analysis of ten studies concluded that isomaltulose consistently reduces postprandial glycemic levels compared to sucrose in diabetic populations, making it a beneficial dietary alternative 5 7 .
Furthermore, recent research highlights its role in stimulating gut hormones like GLP-1 and PYY, which promote satiety and further improve blood sugar control. This "second-meal effect" means that consuming isomaltulose at one meal can lead to a lower glucose spike at the next meal, offering prolonged metabolic stability 4 6 .
The evidence is clear: the choice of carbohydrate matters profoundly. For individuals with Type 1 Diabetes who want to stay active without fear of hypoglycemia, isomaltulose represents a significant advancement. By swapping fast-acting sugars for slow-release isomaltulose before exercise, it is possible to flatten the blood glucose rollercoaster, promote fat burning, and achieve much more stable glycemia during recovery.
This research transforms our understanding of pre-exercise fueling, turning it from a guessing game into a strategic decision that empowers those with T1DM to harness the full benefits of an active lifestyle.