The metabolic response to exercise in insulin-dependent diabetic (IDD) man was assessed during continuous insulin infusion using the subcutaneous (CSII), intravenous (CIVII),and intraperitoneal (CIPII) routes. During the basal period, plasma glucose levels were higher with CIPII (153 ± 17 mg/dl) than with CSII (117 ± 13 mg/dl) or CIVII (118 ± 17 mg/dl). Basal free insulin concentrations were similar for CSII (12.3 ± 10 μU/ml) and CIVII (12.4 ± 1.4 μU/ml) but lower in CIPII (8.5 ± 1.0 (μU/ml, P < 0.05). Exercise on a stationary bicycle at 75 W for 60 min produced a decline of plasma glucose in each protocol that was significant only during CIVII (55 ± 11 mg/dl, P < 0.01). Insulin levels remained unchanged throughout the study period in all protocols. In normals, insulin values decreased during exercise and remained below basal levels through the recovery period (P < 0.05), while plasma glucose remained unchanged. Plasma glucagon and epinephrine levels were similar in all protocols and remained unchanged with exercise, while plasma norepinephrine tended to be higher than normal in all diabetic subjects. Significant differences between normal and diabetic subjects (P < 0.05) were observed for blood ketone bodies, while blood lactate, glycerol, and plasma FFA were similar. Normalization of intermediarymetabolites occurred only with CIVII. Continuous insulin infusion provides near-normal glycemic and metabolic control before, during and following exercise in IDD man. However, to produce normal blood concentrations of intermediary metabolites during exercise, the insulin infusion rate may be excessive in terms of its hypoglycemic effect. CSII appears tobe a safe, accessible, and adequate method for treating diabetic man during exercise.

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