Electrodiagnostic Parameters in Patients With Impaired Glucose Tolerance and Diabetes Mellitus

A Observational Cross Sectional Study to Evaluate the Sensory Nerve Conduction Parameters of the Distal Sensory Nerves in Patients With Impaired Glucose Tolerance and Diabetes Mellitus

The purpose of this study is to evaluate the distal sensory nerves of the feet, namely, the dorsal sural, medial dorsal cutaneous and medial plantar nerves, in patients with impaired glucose tolerance and diabetes mellitus type 2 and compare these parameters to those from healthy participants.

Diabetic Peripheral polyneuropathy (DPP) presents as a slowly progressive primary sensory deficit in length dependent fashion, to result in the classic stocking glove distribution. There is recent evidence to indicate that patients with impaired glucose tolerance ( IGT) on OGTT, the prediabetic stage, have three times the prevalence of distal peripheral polyneuropathy than age matched controls. Patients with IGT, even in their preclinical stages, though they have less severe neuropathy than those with diabetes mellitus, have predominant sensory fiber involvement. To support this, other studies of skin biopsies of IGT patients have shown that microvascular abnormalities and neuropathic changes can occur in the prediabetic stage.

Because DPP is length dependent, it is necessary to evaluate the distal sensory nerves, other than the standard sural and superficial peroneal nerves. To support this theory, recent electrodiagnostic studies in DM patients have shown that albeit normal conduction parameters in the above mentioned two nerves, abnormal parameters can be detected in the more distal sensory nerves, such as the dorsal sural nerve, medial plantar nerves and medial dorsal cutaneous nerve.

Although the importance of evaluating the distal sensory nerves has gained much attention, no study has addressed the issue whether NCS parameters of these distal sensory nerves in IGT patients are significantly different from those of healthy controls with no medical condition, and whether these parameters are different to those with patients with diabetes mellitus, who have no previous history of peripheral polyneuropathy.

With this objective in mind, NCS of the distal sensory nerves of the feet were performed to three groups; normal healthy control group, IGT group and diabetes mellitus group.

Inclusion Criteria:

• For the normal healthy control group
• Healthy participants with normal NCS parameters
• For the IGT group
• Men or women aged 20-70 with IGT referred by the department of endocrinology, with FBS 100-126 mg/dl, post 2 hour OTT - 140-200mg/dl,lasting more than one year.
• Patients willing to undergo NCS.
• For the DM group
• Men or women aged 20-70 with DM type II patients referred by the department of endocrinology, with no previous diagnosis of peripheral polyneuropathy and who showed SNAP amplitudes of the sural and superficial peroneal nerves above 10mA.
• Patients willing to undergo NCS.

Exclusion Criteria:

• No previous diagnosis of any systemic condition related to peripheral polyneuropathy (malnutrition, alcoholic hepatitis, diabetes mellitus( normal group)), no previous medication history, such as chemotherapeutics
• No symptom or sign of peripheral polyneuropathy, no history of tingling sensation, muscle weakness, or gait disturbance
• Skin lesion or swelling that would interfere with NCS conduction
• Previous diagnosis or clinical symptoms that would indicate the presence of mononeuropathy or entrapment neuropathy of the lower extremity.
• Previous trauma episode of the lower extremity
• History of alcohol ( exceeding alcohol consumption of 170g per week ) or substance abuse,
• Pregnancy
• DM group
• Presence of undiagnosed peripheral polyneuropathy determined by screening of the sural and superficial peroneal nerves.