Diabetes, Vol 46, Issue 7 1172-1181, Copyright © 1997 by American Diabetes Association
Long-term intensive therapy of IDDM patients with clinically overt autonomic neuropathy: effects on hypoglycemia awareness and counterregulation
C Fanelli, S Pampanelli, C Lalli, P Del Sindaco, M Ciofetta, M Lepore, F Porcellati, P Bottini, A Di Vincenzo, P Brunetti and GB Bolli
Dipartimento di Medicina Interna e Scienze Endocrine e Metaboliche, Universita degli Studi di Perugia, Italy.
To test the hypothesis that hypoglycemia unawareness and impaired
counterregulation are reversible after meticulous prevention of
hypoglycemia in IDDM patients with diabetic autonomic neuropathy (DAN), 21
patients (8 without DAN [DAN-]; 13 with DAN [DAN+]; of the latter, 7 had
orthostatic hypotension [DAN+PH+] and 6 did not [DAN+PH-]) and 15
nondiabetic subjects were studied during stepped hypoglycemia (plateau
plasma glucose decrements from 5.0 to 2.2 mmol/l) before and 6 months after
prevention of hypoglycemia (intensive therapy). After 6 months, frequency
of mild hypoglycemia decreased from approximately 20 to approximately 2
episodes/patient-month while HbA1c increased from 6.2 +/- 0.3 to 6.9 +/-
0.2% (P < 0.05). Responses of adrenaline improved more in DAN- patients
(from 1.17 +/- 0.12 to 2.4 +/- 0.22 nmol/l) than in DAN+PH- (from 0.75 +/-
0.25 to 1.56 +/- 0.23 nmol/l) and DAN+PH+ patients (from 0.80 +/- 0.24 to
1.15 +/- 0.27 nmol/l, P < 0.05) but remained lower than in nondiabetic
subjects (4.9 +/- 0.37 nmol/l, P < 0.05), whereas glycemic thresholds
normalized only in DAN-, not DAN+. Autonomic symptoms of hypoglycemia
improved but remained lower in DAN- (6.2 +/- 0.6) than in nondiabetic
subjects (8.1 +/- 1.1) and lower in DAN+PH+ (4 +/- 0.8) than in DAN+PH-
subjects (5.1 +/- 0.8, P < 0.05), whereas neuroglycopenic symptoms
normalized (NS). Cognitive function deteriorated less before than after
prevention of hypoglycemia (P < 0.05). Thus, intensive therapy with
emphasis on preventing hypoglycemia reverses hypoglycemia unawareness in
DAN+ patients despite marginal improvement of adrenaline responses, results
in low frequency of hypoglycemia despite impaired counterregulation, and
maintains HbA1c in the range of intensive therapy. We conclude that DAN,
long IDDM duration per se, and antecedent recent hypoglycemia contribute to
different extents to impaired adrenaline responses and hypoglycemia
unawareness.