The effect of walking before and after breakfast on blood glucose levels in patients with type 1 diabetes treated with intensive insulin therapy
Introduction
The benefits of exercise therapy in patients with types 1 and 2 diabetes have been confirmed [1], [2], [3]. It is also known that, although exercise in patients with type 1 diabetes can reduce blood glucose levels, it can also lead to hyperglycemia and ketosis under various conditions, depending on insulin availability [4], [5]. Thus the timing of exercise is important for glycemic control in patients with type 1 diabetes [6]. For example, for patients being treated with intensive insulin therapy, basal insulin concentrations are lowest in the early morning before breakfast. Exercise that occurs in this time period may cause either hypoglycemia or hyperglycemia, depending on the type and duration of exercise. On the other hand, exercise that takes place after breakfast works with the action of the regular insulin injected before the meal. For exercise after meals, the body uses blood glucose as an energy source, and postprandial hyperglycemia is avoided. However, it is also possible that hypoglycemia can occur via the inhibition of release of glucose from glycogenolysis in the liver. Walking, a type of aerobic exercise, is very common and can be done alone or with others as part of the daily routine for many people; similarly, its intensity can be adjusted freely. Although the effect of walking at different times on carbohydrate metabolism has not been clarified sufficiently [7], [8], it is important to know how blood glucose levels fluctuate at the various times when walking may be done. Consequently, we examined the effect of walking before and after breakfast on the blood glucose profile of patients with type 1 diabetes being treated with intensive insulin therapy consisting of the basal-bolus (NPH-human regular) insulin regimen.
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Subjects and methods
Subjects included six non-obese patients (three men, three women) with type 1 diabetes. Characteristics of subjects are shown in Table 1. Written informed consent was obtained from all subjects before enrollment. Subjects were not taking any medications that might affect glucose metabolism and did not have any complications that might prevent them from exercising. All subjects were admitted to the hospital, and stable control of blood glucose levels was achieved (fasting levels: 5.6–11.2 mM) by
Changes in serum glucose and insulin levels before and after walking
At 22:00 h on the previous evening, patients received their usual subcutaneous injection of NPH insulin (mean dose 7.3±3.0 IU; range 4–12 IU). Walking took place after the 06:00 h blood glucose levels were <11.2 mM. Changes in blood glucose concentrations between 07:00 h and 12:00 h are shown in Fig. 1a and changes in insulin concentrations are shown in Fig. 1b. Mean blood glucose values at 07:00 h in the control, ExBM, and ExAM groups were 9.0±1.6, 8.0±2.2, 8.7±1.9 mM, respectively. There were
Discussion
Six patients with type 1 diabetes who received intensive insulin therapy participated in this study to determine the effect of walking before and after breakfast on blood glucose levels. Results indicate that walking after breakfast significantly lowered blood glucose levels during and after walking, then it improved the glycemic control during the morning. In healthy, non-diabetic subjects, exercise slightly lowers glucose levels with subtle decreased insulin concentrations and with slight
References (16)
Nutrition and exercise in individuals with diabetes
Clin. Sports Med.
(1999)- et al.
Moderate-intensity physical activity and fasting insulin levels in women: the Cross-Cultural Activity Participation Study
Diabetes Care
(2000) - et al.
Glycemic responses to exercise in IDDM after simple and complex carbohydrate supplementation
Diabetes Care
(1996) - et al.
Turnover and splanchnic metabolism of free fatty acids and ketones in insulin-dependent diabetics at rest and in response to exercise
J. Clin. Invest.
(1984) Regulation of in vivo ketogenesis: role of free fatty acids and control by epinephrine, thyroid hormones, insulin and glucagon
Diabetes Metab.
(1996)- et al.
Nutrition management of insulin-dependent diabetes mellitus in adults: review by the diabetes care and education dietetic practice group
J. Am. Diet Assoc.
(1993) - et al.
Walking to health
Sports Med.
(1997) Physical activity and the prevention of type 2 diabetes mellitus: how much for how long?
Sports Med.
(2000)