Improvement of metabolic control does not normalize auditory brainstem latencies in subjects with insulin-dependent diabetes mellitus.
BACKGROUND
In our previous study (Am J Otolaryngol 14:413-418, 1993), we reported that prolonged auditory brainstem response latencies are associated with microvascular complications and the duration of diabetes in patients with insulin-dependent diabetes mellitus (IDDM). To investigate whether short-term improvement in metabolic control also affects ABR-responses, we compared ABR-latencies in subjects with IDDM before and after intensified insulin and diet therapy.


METHODS
Auditory brainstem latencies were measured in 13 subjects with IDDM (mean age: 25 years) before and after intensified insulin and diet therapy. The acoustic stimulus was a half sine wave with a duration of 0.250 millisecond and a frequency of 2,000 Hz. The stimulus was presented monaurally with fixed polarity through shielded headphones TDH-39 at repetition rate of 10 Hz and at 90 dB hearing level. All subjects had normal hearing ability. Glycated hemoglobin A1C (GHbA1C), blood glucose immediately before ABR-measurements, and mean blood glucose during 24 hours before auditory studies were measured before and after intensified therapy.


RESULTS
During intensified insulin therapy, GHbA1C improved significantly (P < .05) in study subjects. However, no changes were observed in ABR-latencies. We also studied those 10 patients whose blood glucose improved during intensified insulin therapy. Although blood glucose was significantly lower (P < .01) after intensified insulin therapy compared with that at baseline, no changes were observed between ABR-latencies at baseline and follow-up.


CONCLUSIONS
ABR-latencies were not affected by improvement in metabolic control in patients with IDDM. Our finding suggests that delayed ABR-latencies found in patients with IDDM are not caused by poor metabolic control of diabetes but rather by other mechanisms, for example, microvascular complications.
Virtaniemi
J
J
Department of Otolaryngology, University of Kuopio, Finland.
Kuusisto
J
J
Karjalainen
L
L
Karjalainen
S
S
Laakso
M
M
D000328:Adult; D001301:Audiometry, Pure-Tone; D001786:Blood Glucose / Q000032:analysis*; D002096:C-Peptide / Q000032:analysis; D002853:Chromatography, Liquid; D003922:Diabetes Mellitus, Type 1 / Q000097:blood* / Q000378:metabolism* / Q000628:therapy; D016057:Evoked Potentials, Auditory, Brain Stem; D006801:Humans; D011863:Radioimmunoassay
D001786:Blood Glucose; D002096:C-Peptide