Early parasympathetic neuropathy associated with elevated fasting plasma C-peptide concentrations and late parasympathetic neuropathy with hyperglycaemia and other microvascular complications.
OBJECTIVE
To examine the relationship between parasympathetic neuropathy, hyperinsulinaemia, glycaemic control (HbA(1c)), and future diabetic complications.


METHODS
We assessed parasympathetic nerve function [expiration/inspiration (E/I) ratio], glomerular filtration rate (GFR), glycaemic control (HbA(1c)), fasting plasma (f-p-) C-peptide in 82 Type 2 diabetic patients (age 61 +/- 1 years) 5 and 12-15 years after diagnosis. Diabetic retinopathy was assessed 15 years after diagnosis.


RESULTS
High HbA(1c) values in the first study were associated with retinopathy (with 8.6 +/- 2.0 vs. without retinopathy 6.2 +/- 1.9%; P < 0.0001) and disturbed parasympathetic nerve function (low E/I ratio; r(s) = -0.41; P = 0.0061) in the second study, as well as with deteriorations in GFR between the first and second study (r(s) = 0.62; P < 0.0001). Patients with parasympathetic neuropathy in the first study had significantly higher f-p-C-peptide concentrations than those without 3 years (1.20 +/- 0.43 vs. 0.86 +/- 0.40 nmol/l; P = 0.0015) and 5 years (1.20 +/- 0.44 vs. 0.82 +/- 0.33 nmol/l; P < 0.0001), but not 15 years after diagnosis.


CONCLUSIONS
High HbA(1c) values 5 years after diagnosis of Type 2 diabetes were associated with retinopathy, disturbed parasympathetic nerve function, and deterioration in GFR 7-10 years later. Parasympathetic neuropathy 5 years after diagnosis was associated with high C-peptide concentrations. Parasympathetic nerve function has to be considered when beta-cell function is evaluated. Hyperglycaemia is an important factor for the development of complications in Type 2 diabetes.
Gottsäter
A
A
Department of Vascular Diseases, University of Lund, University Hospital MAS, Malmo, Sweden. anders.gottsater@skane.se
Kangro
M
M
Sundkvist
G
G
D001342:Autonomic Nervous System Diseases / Q000097:blood*; D001786:Blood Glucose / Q000032:analysis*; D002096:C-Peptide / Q000097:blood*; D003924:Diabetes Mellitus, Type 2 / Q000097:blood*; D003930:Diabetic Retinopathy / Q000097:blood; D005215:Fasting; D005260:Female; D005500:Follow-Up Studies; D005919:Glomerular Filtration Rate; D006442:Glycated Hemoglobin / Q000032:analysis; D006339:Heart Rate; D006801:Humans; D007328:Insulin / Q000097:blood; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D018709:Statistics, Nonparametric; D013997:Time Factors
D001786:Blood Glucose; D002096:C-Peptide; D006442:Glycated Hemoglobin; D007328:Insulin