PROTEIN-CONTENT OF THE EVENING MEAL AND NOCTURNAL PLASMA-GLUCOSE REGULATION IN TYPE-I DIABETIC SUBJECTS

The effect of two isocaloric evening meals (low protein-high fat vs. h igh protein-low fat content) on plasma glucose regulation during the n ight were compared. Eight C-peptide-deficient type-I diabetic subjects without autonomic neuropathy were treated with fixed doses of continu ous infusions of insulin during 2 nights. At 7 p.m. they received in r andom order either a low protein-high fat (5% of total energy protein, 60% fat, 35% carbohydrate) or a high protein-low fat (35% protein, 30 % fat, 35% carbohydrate) evening meal. Venous plasma samples were draw n hourly thereafter. Plasma glucose concentrations were similar postpr andially during the 2 nights between 7 p.m. and 11 p.m., but they were higher in the early morning hours after the high protein meal (p < 0. 02 vs. the low protein meal). Two subjects developed symptomatic hypog lycemia after the low protein meal. Plasma glucagon concentrations wer e higher (p = 0.023) and serum free insulin lower (p < 0.05) after the high protein-low fat meal. Plasma cortisol and growth hormone were no t significantly different between the two diets. Therefore, an increas e in the protein content of the evening meal (fat content diminished) increases plasma glucose concentrations several hours later in the nig ht, possibly due to protein-induced glucagon secretion and to lower pl asma free insulin levels. Patients with type-I diabetes with a tendenc y to develop hypoglycemia during the night may avoid this problem by i ncreasing the protein content of the evening meal.