Glucose Response to Intense Aerobic Exercise in Type 1 Diabetes: Maintenance of near euglycemia despite a drastic decrease in insulin dose

doi:10.2337/diacare.26.4.1316

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Letters: Observations
Letter

Glucose Response to Intense Aerobic Exercise in Type 1 Diabetes

Maintenance of near euglycemia despite a drastic decrease in insulin dose

Franck Mauvais-Jarvis, MD¹, Eugène Sobngwi, MD¹, Raphaël Porcher, PHD², Jean Pierre Garnier, PHD³, Patrick Vexiau, MD¹, Alain Duvallet, MD⁴ and Jean-François Gautier, MD, PHD¹

¹ Department of Endocrinology and Diabetes, Saint-Louis Hospital, Paris, France
² Department of Biostatistics and Medical Informatics, Saint-Louis Hospital, Paris, France
³ Department of Biochemistry, Saint-Louis Hospital, AP-HP and Faculty of Pharmacy; University of Paris, Paris, France
⁴ Department of Exercise Physiology, University of Paris VII School of Medicine, Tarnier Hospital, Paris, France

In patients with type 1 diabetes, hypoglycemia or degradationin blood glucose control may occur during and after physicalexercise (1–3). This may be avoided in patients with goodglycemic control by decreasing insulin doses and/or ingestingcarbohydrate. Although most sport activities involve intensemuscle exercise, current recommendations are based on studieson moderate exercise (4). We therefore investigated the effectof a drastic reduction in insulin dose before a 60-min high-intensitycycle exercise in 12 subjects with uncomplicated type 1 diabetes(age 32 ± 7 years, BMI 23 ± 7 kg/m², HbA_1c 7.2± 3.8%, and VO_2max 40 ± 27 ml · min^-1 ·kg^-1 [mean ± SD]). Six patients were treated with threedaily injections (regular insulin in the morning and at noonand mixed regular NPH insulin before dinner). The six remainingpatients were treated with two daily injections (30% regular/70%NPH insulin). After determination of VO_2max, patients reportedto the laboratory on two separate occasions, 1 week apart, inrandomized order 90 min after breakfast (60 g carbohydrates,10 g lipids, and 8 g proteins) to perform a 60-min exercisesession on an ergocycle at 70% VO_2max. On one occasion, exercisewas performed with the usual morning insulin dose. On the other,morning insulin dose was reduced by 90% for patients treatedwith three daily injections and by 50% for patients treatedwith two injections per day. Power output was monitored andstrictly maintained during the tests to correspond to $~$ 70% VO_2max.

Changes in plasma glucose (PG) levels were analyzed by a mixed-modelANCOVA, with a random subject effect and random coefficientsfor time within each subject, using the SAS version 6.12 softwarepackage (SAS Institute, Cary, NC).

At the beginning of exercise and over the test period, PG levelswere higher in the experimental condition with insulin dosereduction (P < 0.0001) (Fig. 1). Changes in PG levels weresimilar in both conditions during exercise and recovery (P =0.99). No difference was observed when considering insulin regimen.During exercise, the mean decrease in PG concentrations was-0.085 ± 0.012 mmol · l^-1 · min^-1 (mean± SE) (P < 0.0001), whereas no significant variationwas observed during the recovery period. When exercise was performedwithout reducing insulin doses, eight patients (66%) had hypoglycemiaand were given oral sucrose (22 ± 3 g). Changes in plasmalactate, growth hormone, cortisol, glucagon, and norepinephrinewere not statistically different. The peak of plasma epinephrineconcentration was higher in the test without insulin reduction:2.3 ± 1.5 vs. 1.1 ± 0.7 nmol/l (P < 0.04, Student’st test).

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Figure 1— Changes in PG levels during exercise and recovery performed with ( ${blacksquare}$ ) and without ( ${square}$ ) insulin reduction. Of 12 patients, 8 received oral glucose during the condition without insulin reduction. Data are expressed as mean ± SE (n = 12).

In previous studies, decreasing insulin dose before moderateexercise ( $~$ 55% VO_2max) was not associated with degradation inblood glucose control during and after exercise (1,4,5). However,most sport activities, whether individual (running, biking,hiking, and swimming) or team (basketball, football, and handball)involve intense muscle exercise. We show here that a 90% reductionof morning regular insulin before intense exercise allows themaintenance of near normal blood glucose levels without occurrenceof hypoglycemia. When insulin was not reduced, two-thirds ofpatients experienced hypoglycemia.

This study emphasizes the importance of insulin-independentcontraction-induced glucose uptake by muscle, previously demonstratedin healthy men (6) and mice lacking muscle insulin receptor(rev. in 7).

In conclusion, we demonstrate that type 1 diabetic patientscan perform intense muscle exercise after a 50–90% reductionin insulin dose, depending on their insulin regimen. This decreaseprevents hypoglycemia without worsening metabolic control. Suchadvice could be given to young type 1 diabetic patients engagedin sports activities.

Footnotes

Address correspondence to Dr. Jean-François Gautier,Department of Endocrinology and Diabetes, Saint-Louis Hospital,1, Avenue Claude Vellefaux, 75010 Paris, France. E-mail: j-fgautier{at}wanadoo.fr.

References

Berger M, Berchtold P, Cuppers HJ, Drost H, Kley HK, Muller WA, Wiegelmann W, Zimmerman-Telschow H, Gries FA, Kruskemper HL, Zimmermann H: Metabolic and hormonal effects of muscular exercise in juvenile type diabetics. Diabetologia 13: 355–365, 1977[Medline]
Koivisto VA, Felig P: Effects of leg exercise on insulin absorption in diabetic patients. N Engl J Med 298: 79–83, 1978[Abstract]
Horton ES: Role and management of exercise in diabetes mellitus. Diabetes Care 11: 201–211, 1988[Abstract]
Schiffrin A, Parikh S: Accommodating planned exercise in type I diabetic patients on intensive treatment. Diabetes Care 8 337–342, 1985[Abstract]
Schmulling RM, Jakober B, Pfohl M, Overkamp D, Eggstein M: Exercise and insulin requirements. Horm Metab Res Suppl 24: 83–87, 1990[Medline]
Wasserman DH, Geer RJ, Rice DE, Bracy D, Flakoll PJ, Brown LL, Hill JO, Abumrad NN: Interaction of exercise and insulin action in humans. Am J Physiol 260: E37–E45, 1991[Abstract/Free Full Text]
Mauvais-Jarvis F, Kulkarni RN, Kahn CR: Knockout models are useful tools to dissect the pathophysiology and genetics of insulin resistance. Clin Endocrinol (Oxf) 57: 1–9, 2002[Medline]