Total vascular risk as a strong correlate of severity of diabetic peripheral neuropathy in Nigerian Africans

HbA1c, commonly utilised in Caucasian studies, is an inconsistent risk marker for the severity of diabetic peripheral neuropathy (DPN) severity. Other vascular risk factors have been shown to affect DPN. However, no study has examined the relative impact of HbA1c and total cardiovascular risk load (TCRL) on DPN severity. Using the United Kingdom Prospective Diabetes Study cardiovascular risk engine as a measure of TCRL, we sought to determine if TCRL is a better correlate of DPN severity than HbA1c alone.

We studied 277 consecutive consenting black type 2 diabetes mellitus (DM) patients in Nigeria. We defined DPN using Michigan Neuropathy Screening Instrument thresholds defined by prior validation studies. Severity of DPN was measured using the modified Dyck's grading, which had been previously validated in Nigeria. Patients with non-diabetic causes of neuropathy were excluded.

197 (71.1%) patients had DPN. The mean HbA1c value was 6.9%. The HbA1c correlated significantly to the fasting plasma glucose (r = .36), but did not correlate significantly to the DPN severity (P = .304, rho = .075). The TCRL had the strongest significant correlation to DPN severity (P = < .001, rho = .285). Age and dyslipidemia, which are also components of the TCRL, emerged as independent statistical predictors of DPN severity in multivariate analysis.

In Nigerian Africans, TCRL was a stronger statistical correlate of DPN severity than HbA1c. In the setting of multiracial studies, the development of a special risk engine for monitoring the risk of DPN is recommended as a substitute for HbA1c alone.