Association of Vitamin D Level with Diabetic Peripheral Neuropathy

Abstract

Background: Diabetes mellitus causes a range of nerve damage referring to diabetic neuropathy. Diabetic peripheral neuropathy (DPN) affects over 132 million individuals worldwide (about 1.9% of the population). Diabetes is the largest recognized cause of neuropathy in affluent countries, and the most prevalent consequence and reason for morbidity and mortality. The deficient vitamin D value is one of the newest considerations of the development of diabetes and peripheral neuropathy. Objective: The objective of this study was to compare vitamin D levels among Type 2 diabetes mellitus patients with/without diabetic peripheral neuropathy and to find an association of Vitamin D levels with diabetic peripheral neuropathy based on the Michigan Neuropathy Screening Instrument (MNSI) score at a tertiary care hospital, Peshawar. Methods: A case-control study was conducted from August 2021 to October 2021 after taking approval from the ethical committee of Prime foundation Pakistan, Mercy Teaching Hospital Peshawar. Patients with type 2 diabetes were recruited and then divided into two groups using the purposive sampling technique. Type 2 diabetes with neuropathy included group A Patients (Cases), while type 2 diabetes without neuropathy included group B (Controls). Both groups had 49 study subjects each based on convenience. A physical examination was conducted to prove the diagnosis of diabetic peripheral neuropathy (DPN) using the Michigan Neuropathy Screening Instrument (MNSI). Patients screening positive on the MNSI (>2 points out of a 10-point scale) were considered neuropathic. Serum vitamin D levels were assessed in both patients (cases) and controls using a hospital laboratory and labeled as Vitamin D sufficiency (more than 30ng/ml), Vitamin D deficiency (<20 ng/ml), Higher Vitamin D (100 ng/ml) and vitamin D insufficiency (between 20 and 30 ng/ml). Results: A total of 98 subjects were enrolled in the study with a 1:1 ratio of cases and controls. Median age [57 (IQR 52-65) versus 55 (IQR=48-61), p<0.001] and disease duration [10 (IQR=8-16) versus 7 (IQR=4-10), p<0.001] were significantly different among cases and control respectively. The proportion of patients with normal vitamin D levels was significantly lower in cases than in control (10.2% versus 67.3%, p<0.001). On the multivariable regression model, vitamin D levels were found to be an independent predictor of DPN with a significantly lower risk of DPN among patients with normal vitamin D levels as compared to those who had vitamin d higher than 100 ng/ml (OR=0.19, 95% CI:0.001-0.282, p=0.004). Conclusion: Our study concluded that patients with Type 2 diabetes mellitus DPN have deficient levels of Vitamin D as assessed by Michigan Neuropathy Screening Instrument. Considerable risk of Diabetic peripheral neuropathy among patients having a deficiency of Vitamin D was proved.