Muscle triglycerides in diabetic subjects. Effect of insulin deficiency and exercise

Muscle triglycerides and glycogen were measured in biopsy specimens of the vastus lateralis muscle before and after 1 h of ergometric exercise at 50 to 60% of maximal capacity (i. e. at a pulse rate during exercise of 180 minus age) in 3 groups of 19 to 35 year old, non-obese male subjects: 10 normals, 10 insulin dependent diabetic patients in relatively good control and 10 poorly controlled insulin dependent diabetic patients in whom insulin was withdrawn 24 h prior to examination. At rest in all subjects muscle triglyceride content was positively correlated with serum triglycerides(p < 0.001) and blood glucose (p < 0.05), resulting in elevated muscle triglyceride stores in the insulin deficient diabetic patients (17.9 +/- 1.8 mumol/g protein vs. 13.4 +/- 1.3 and 9.4 +/- 1.2 in the normal subjects and the well controlled diabetic patients; p < 0.05 and < 0.001). During exercise, utilisation of muscle triglycerides and glycogen were directly related to content at rest (p < 0.001), including the insulin-deprived patients with decreased glycogen. The decrease of muscle fat was associated with a rise in serum glycerol (p < 0.001) and non-esterified fatty acids (p < 0.001) during exercise.