Direct assessment of muscle glycogen storage after mixed meals in normal and type 2 diabetic subjects

P. E. Carey, J. Halliday, J. E. M. Snaar, P. G. Morris, R. Taylor
2003 American Journal of Physiology. Endocrinology and Metabolism  
assessment of muscle glycogen storage after mixed meals in normal and type 2 diabetic subjects. To understand the day-to-day pathophysiology of impaired muscle glycogen storage in type 2 diabetes, glycogen concentrations were measured before and after the consumption of sequential mixed meals (breakfast: 190.5 g carbohydrate, 41.0 g fat, 28.8 g protein, 1,253 kcal; lunch: 203.3 g carbohydrate, 48.1 g fat, 44.0 g protein, 1,497.5 kcal) by use of natural abundance 13 C magnetic resonance
more » ... opy. Subjects with diet-controlled type 2 diabetes (n ϭ 9) and ageand body mass index-matched nondiabetic controls (n ϭ 9) were studied. Mean fasting gastrocnemius glycogen concentration was significantly lower in the diabetic group (57.1 Ϯ 3.6 vs. 68.9 Ϯ 4.1 mmol/l; P Ͻ 0.05). After the first meal, mean glycogen concentration in the control group rose significantly from basal (97.1 Ϯ 7.0 mmol/l at 240 min; P ϭ 0.005). After the second meal, the high level of muscle glycogen concentration in the control group was maintained, with a further rise to 108.0 Ϯ 11.6 mmol/l by 480 min. In the diabetic group, the postprandial rise was markedly lower than that of the control group (65.9 Ϯ 5.2 mmol/l at 240 min, P Ͻ 0.005, and 70.8 Ϯ 6.7 mmol/l at 480 min, P ϭ 0.01) despite considerably greater serum insulin levels (752.0 Ϯ 109.0 vs. 372.3 Ϯ 78.2 pmol/l at 300 min, P ϭ 0.013). This was associated with a significantly greater postprandial hyperglycemia (10.8 Ϯ 1.3 vs. 5.3 Ϯ 0.2 mmol/l at 240 min, P Ͻ 0.005). Basal muscle glycogen concentration correlated inversely with fasting blood glucose (r ϭ Ϫ0.55, P Ͻ 0.02) and fasting serum insulin (r ϭ Ϫ0.57, P Ͻ 0.02). The increment in muscle glycogen correlated with initial increment in serum insulin only in the control group (r ϭ 0.87, P Ͻ 0.002). This study quantitates for the first time the subnormal basal muscle glycogen concentration and the inadequate glycogen storage after meals in type 2 diabetes.
doi:10.1152/ajpendo.00471.2002 pmid:12453829 fatcat:iqiltighvfeglp7vtakvjxo7w4