Diabetes, Vol 35, Issue 1 78-82, Copyright © 1986 by American Diabetes Association
Pathogenesis and prevention of the dawn phenomenon in diabetic patients treated with CSII
VA Koivisto, H Yki-Jarvinen, E Helve, SL Karonen and R Pelkonen
The mechanism of the dawn phenomenon was studied in 12 C-peptide-negative
type I diabetic patients (age 30 +/- 2 yr) treated with continuous
subcutaneous insulin infusion. During constant basal infusion, nocturnal
glycemia remained constant until 4 a.m., but began to rise thereafter in
10/12 patients, with the mean rise from 4.6 +/- 0.4 mmol/L to 6.1 +/- 0.7
mmol/L (P less than 0.01) by 8 a.m. In these patients the rate of glucose
production (Ra, 2.14 +/- 0.04 mg/kg/min, 3-H3-glucose infusion) exceeded
the rate of utilization (Rd, 1.89 +/- 0.03 mg/kg/min, P less than 0.02).
When the patients were restudied after the infusion rate was increased by
49 +/- 7%, Ra fell to 1.75 +/- 0.03 mg/kg/min (P less than 0.01) and the
dawn phenomenon was abolished. However, both Ra and Rd remained higher in
the diabetic subjects (P less than 0.05) than in eight healthy control
subjects, in whom Ra (1.66 +/- 0.02 mg/kg/min) was equal to Rd with
glycemia remaining unchanged. Peripheral free insulin levels in the
diabetic patients were similar during constant (12.3 +/- 0.5 mU/L) and
increased infusion rate (11.3 +/- 0.4 mU/L), and higher than those of the
control subjects (5.2 +/- 0.2 mU/L, P less than 0.05). A diurnal rise in
serum cortisol levels occurred 1 h earlier in the diabetic than in the
control subjects, and Ra was directly proportional to serum cortisol
concentration (r = 0.61, P less than 0.01). Serum growth hormone levels
were also slightly higher in the diabetic than the control
subjects.(ABSTRACT TRUNCATED AT 250 WORDS)