Prolonged Exercise and Its Effects on Type 1 Diabetes Mellitus

Type 1 diabetes mellitus is presumably caused by immunological or viral cumulative destruction of pancreatic β cells, leading to a complete inability to produce endogenous insulin. Exercise can cause different reactions in relation to blood glucose concentration, depending on duration and intensity. High intensity aerobic workouts can cause blood glucose to drop. Anaerobic exercise can cause blood glucose to rise. This can cause problems for a diabetic patient in terms of diabetes management during exercise, as patients often over-compensate for an expected glucose drop by eating carbohydrates and taking a reduced bolus amount of insulin (or no insulin at all) in anticipation of a sharp blood glucose drop. After about ten seconds of anaerobic exercise, energy production moves from creatine phosphate break-down to anaerobic glycolysis, although glycolysis only generates energy for about 180 seconds. An endurance event, such as long-distance backpacking, primarily utilizes aerobic respiration. There is a low rate of aerobic ATP generation, but energy can be sustained for far longer than glycolysis or the phosphagen system. Due to this inefficiency, backpackers may have nutritional deficits of nearly 3,000 calories/day. Caloric deficit should not affect blood glucose levels if insulin ratios are adjusted accordingly. Typically, diabetics with greater fitness require less insulin and do not suffer large blood glucose decreases when compared to less fit peers, although insulin dosages are commonly decreased down to levels as low as 30% of the patient's normal rates. As the body adjusts to the demands of backpacking, blood glucose and insulin requirements normalize.