Value of the Oral Glucose Tolerance Test in the Evaluation of Chronic Idiopathic Axonal Polyneuropathy

Abstract

Background: An underlying cause is found in only 7% to 30% of patients with chronic idiopathic axonal polyneuropathy (CIAP). Diabetes mellitus, inherited disorders, toxin exposure, and primary amyloidosis are the most common identified causes of sensory neuropathies affecting both large and small myelinated fibers. Undiagnosed impaired fasting glucose metabolism has been associated with CIAP at a higher frequency rate than in the general population. This increased prevalence rate was identified using the 2-hour oral glucose tolerance test (2h-OGTT) and a previous version of the American Diabetes Association (ADA) guidelines. Objectives: To determine the prevalence of abnormal fasting glucose metabolism in patients with CIAP and to compare the value of determining fasting plasma glucose levels using revised (2003) ADA criteria with the 2h-OGTT for predicting abnormal fasting glucose metabolism. Patients: In this 24-month retrospective study, 100 consecutive patients were identified with no known cause for CIAP, including diabetes mellitus, between January 2003 and January 2005. All had both a fasting plasma glucose test and a 2h-OGTT in addition to a complete neurological examination. Neurophysiological studies, computer-assisted sensory examination, and quantitative sudomotor axonal reflex testing were used to classify CIAP into subtypes according to nerve fiber involvement. Results: The prevalence of undiagnosed abnormal fasting glucose metabolism was found to be nearly 2-fold higher (62%) in patients with CIAP than in similar age-matched general population groups (33%). Using the 2003 revised ADA criteria, 39 patients (39%) had abnormal fasting plasma glucose metabolism (36 with impaired fasting glucose, 3 with diabetes mellitus), while the 2h-OGTT provided an even higher diagnostic rate of 62% (62 patients; PϽ.001) of impaired fasting glucose metabolism (38 with impaired glucose tolerance, 24 with diabetes mellitus). The abnormal glucose metabolism rates were found to be similar across the 3 subtypes (sensorimotor, pure sensory, and small-fiber neuropathy) of CIAP (P=.60, .72, and .61). Conclusions: This study adds to emerging evidence that abnormal glucose metabolism may be a risk factor for CIAP. Even with revised (2003) ADA criteria, the 2h-OGTT provides additional diagnostic information to the health care professional in the evaluation of CIAP. Subtypes of CIAP are equally likely to have abnormal glucose metabolism.

Evidence of Nerve Conduction Defects in Type-II Diabetic Patients without Neuropathic Symptoms

“…In the symptomatic subjects as shown in 13 . They are also said to be more prone to development of Polyneuropathy.…”

“…But there is a possibility of subclinical involvement of nerves, which can be detected by electrophysiological study of nerve conduction. Defective nerve conduction is also believed to precede progression to symptomatic diabetic neuropathy at a later stage 13 .…”

Comparative Efficacy of Duloxetine Versus Nortriptyline in Patients with Diabetic Peripheral Neuropathic Pain: A Double Blind Randomized Controlled Trial

“…Approximately 10 to 20% of patients with diabetes have DPNP that worsens at night (1,2). Diabetic peripheral neuropathy is diagnosed with pain feeling in lower extremities in diabetic patients (3). However, other potential causes of peripheral pain including vitamin B12 deficiency, claudication, and osteoarthritis should be considered (4).…”

Pre-Diabetes; Prevalence of Pre-Diabetes in Our Local Population.

“…[6][7][8] Evidence is accumulating on increased prevalence of idiopathic polyneuropathy among prediabetic individuals. 9,10 Moreover, regression from prediabetes to normal glucose regulation has been associated with long-term reduction in diabetes and CVD risk.…”