Vitamin D Deficiency, Atherogenic Index and Some Demographis Data as Risk Factors with The Prevelance of Diabetic Peripheral Polyneuropathy in Type II Diabetic Females

Methods: This study was conducted at the Clinical Physiology Laboratory and Diabetes Research Center of King Abdul Aziz University Hospital (Riyadh, Saudi Arabia) , between January 2018 to May 2019 ,involved 15 subjects with controlled diabetes ,30 diabetic patients with possible DPN and 50 diabetic patient with DPN.Electrophysiological nerve conduction studies and serum 25(OH)D ,lipid profile and HbA1c were measured.

Hyperglycemia may affect the peripheral sensory nerves through several mechanisms to induce diabetic neuropathy. The increased intracellular sorbitol accumulation decreased neuronal blood flow, and peripheral nerve hypoxia in hyperglycemia can cause direct neuronal damage [5]. The auto-oxidation of glucose induces endothelial damage through increased production of Reactive Oxygen Species (ROS), and advanced glycation end products. induces vasoconstriction and reduces neuronal blood flow by activation of protein kinase C [6]. Vitamin D is an essential hormone obtained from the diet or skin synthesis. It can be hydroxylated in the liver into 25-hydroxyvitamin D (25[OH]D), then converted to its active form by 1-hydroxylation in the renal proximal tubules into 1,25 dihydroxyvitamin D (1,25[OH]D) [7]. Studies have confirmed the occurrence of low serum 25(OH)D levels in patients with chronic kidney disease [7]. Vitamin D has a classical function in maintaining calcium and phosphate homeostasis, but also it has a potential role in maintaining immunity, vascular function, cardiomyocyte health, inflammation, insulin resistance and in lowering the urinary albumin concentration in patients with chronic kidney disease [8].
Celil et al. [9] have been stated that Vitamin D is a known suppressor of renin biosynthesis, and vitamin D deficiency has been associated with progression of Chronic Kidney Disease (CKD).
Patients with type 2 diabetes and CKD have an exceptionally high rate of severe 25-OH vitamin D deficiency. Low vitamin D levels are suggested to be associated with different impaired glucose metabolism states including diabetes mellitus. Vitamin D deficiency is supposedly higher in type 2 diabetic patients compared to healthy individuals [10]. Vitamin D deficiency contributes to the etiology and progression of type 2 diabetes. 25-OH vitamin D concentrations were found to be lower in patients with type 2 diabetes with impaired glucose tolerance than in controls [10].
Diabetic nephropathy is a major microvascular complication of diabetes mellitus [11]. Animal studies have shown that calcitriol supplement can reduce albuminuria in mice with diabetic nephropathy [11].
The relation of Vit D with diabetes complications is poorly studied in Saudi Arabia and needs to be more illucidated.
Dyslipidemia describes as elevated plasma concentration of lipid (Triglyceride (TG) and Total Cholesterol (TC) and their blood transporting lipoproteins (HDL-Cholesterol, LDL-Cholesterol, VLDL-Cholesterol). There is a strong association between incidence of CVD and high level of LDL-C and also low level of HDL-C ,therefore the LDL-C/ HDL-C ratio is often calculated to estimate cardiovascular risk as indicated by strong scientific evidence .On the other hand, high level of TG has been related with an increased LDL-C particles and increased cardiovascular risk [12]. On that basis, atherogenic dyslipidemia, defined as high LDL-C/HDL-C ratio and hyper TG, is associated with high cardiovascular risk [12]. Atherogenic Index (AI) is inversily related and significantly correlated with insulin sensitivity, and it has been reported that AI correlates with insulin resistance (HOMA-IR) [13]. But AI relation to DPN needs more investigations to be clarified and highlighted. To the best of our knowledge, the correlation of vitamin D deficiency as a risk factor in patients with diabetic peripheral neuropathy is rarely investigated in Saudi diabetic patients, so it remains unclear and needs to be illucidated. The goal of the present study is to evaluate a possible association between vitamin D deficiency and DPN. Also the current study aimed to determine the correlation

Methods
This observational cross-sectional study was conducted at

Variables and Data Collection
In this cross-sectional study a total of 150 eligible outpatient who had initially agreed to participate were enrolled and identified, The final analysis was performed based on data obtained from the remaining 95 participants. Prior to the start of the study, they received information about the study and its aims and gave their informed consent to participate. Peripheral neuropathy (DPN) was defined based on certain criteria: symptoms, signs abnormal NCS (defined as abnormal median, Sural or Peroneal motor or sensory amplitude or motor and sensory conduction velocity using age adjusted normative data). subjects who fulfilled 0 criteria were classified as having no neuropathy. We found 5 patients has no signs and symptoms of DPN or other criteria of DPN according to electrophysiological findings, they were included as a control group. In this study DPN was defined according to the presence of peripheral sensorimotor neuropathy symptoms plus abnormal nerve conduction in at least 2 peripheral nerves.
Those fulfilling 1-2 criteria were defined as early possible neuropathy (they have either only signs& symptoms or have signs& symptoms plus abnormal nerve conduction in only one peripheral nerve), they were 30 patients. Those fulfilling three or more (e.g. symptoms and signs in addition to one confirmatory test, symptoms or signs in addition to two or more confirmatory tests, or "laboratory based" diagnosis based on three confirmatory tests without signs or symptoms). Patients with clinical neuropathy were diagnosed on the basis of: abnormal electrodiagnostic tests with decreased nerve conduction velocity (NCV), or decreased amplitudes, or prolonged sensory or motor distal latencies, and abnormal quantitative sensory tests for vibration, tactile, thermal warming, and cooling thresholds. They were defined as patients with DPN with neuropathy and were 50 patients.  ng/ml is considered normal, 10-24 ng/ml is considered mild to moderate deficiency but levels less than 10 ng/ml is considered severe vitamin D deficiency [14]. Measurements of distance, response latencies, and amplitude were carried out in a standard fashion using onset latencies, and base line to peak amplitude. Measurements of peak-peak amplitudes

Quantitative Sensory and Motor
were used for sensory responses [15]. Sensory nerve conduction.
The sensory nerve action potential (SNAP) of the median nerve was measured by the antidromic technique on the index finger with ring electrodes placed 2.5 cm apart. The fixed distal distance for sensory NCV was 20 mm proximal to the distal wrist crease and for ulnar was measured by antidromic technique on the little finger.
The sural SNAPs were recorded behind the lateral malleolus on the posterior lateral aspect of the leg, 14 cm from the active electrode with a fixed distal distance of around 140 mm above the recording electrode [16]. Sensory nerve action potential latency, amplitude and conduction velocity were measured. Motor nerves conduction.
The compound muscle action potentials (MNAP) of the median were obtained using supramaximal stimulation of the nerves at the wrist and elbow, with the distal distance for motor NCV 80 mm above the recording electrode and for ulnar nerve was done at wrist and elbow [15]. All data were reported as mean±SD.

Discussion
The findings of the present study reveals a significant deficiency of Vit D in group III ( late DPN) compared to early DPN (group I) and Rasheed MA et al. [17] stated that altered VitD levels may play a role in the pathogenesis of T2DM and its microvascular

complications. Altered expression of Vit D receptors Notch2
and VDR polymorphisms may play a role in the development of microvascular complications as DPN in diabetic patients. These results may assist in early identification and management of diabetic complications may be by vit D supplementation [17].
Vitamin D deficiency is an important risk factor for glucose intolerance and contributes to the etiology and progression of type 2 diabetes .Recent studies have shown impaired insulin synthesis and secretion in animal models with vitamin D deficiency; diabetes onset can be delayed with 1-25-OH vitamin D intake. Also,1-25-OH vitamin D concentrations were found to be lower in patients with type 2 diabetes with impaired glucose tolerance than in controls [18]. Vitamin D is a known suppressor of renin biosynthesis, and vitamin D deficiency has been associated with progression of chronic kidney disease (CKD) and diabetic nephropathy. Patients with type 2 diabetes and CKD have an impaired microvascular circulation due to exceptionally high rate of severe 1-25-OH vitamin D deficiency [18]. These findings could explain the cause for occurrence of DPN in vit D deficiency group.
Wu C et al. [19] showed that vitamin D supplementation was associated with reduced HbA1c levels among patients with 25-hy- In the present study, the relationship between glycemic control, BMI, diabetes duration and atherogenic index with major features of neuropathy was examined in a cohort of female participants with type 2 diabetes to better understand risk factors for early possible neuropathy development versus patients with well-established and more advanced neuropathy. There were significant differences in key measures of neuropathy severity as median, ulnar, tibial and Peroneal motor latency and conduction velocity also sensory median and sural latency and sensory amplitude between diagnostic groups that with possible early DPN and actual DPN group ( Table   4). There were significant differences between each of the two diagnostic groups for DPN measures at the arm, foot and distal leg.
These findings suggest that both sensory and motor large myelinated nerve fibers are affected in the course of neuropathy. The correlation data suggests there may be differential impact of diabetic duration, dyslipidemia, obesity and hyperglycemia on individual neuropathy measures. The current study stated that high BMI is a risk factor for DPN., this is in accordance to the findings of Herman et al. [23] study who compared obese and thin subjects , they have shown relative abnormalities of both nerve conduction measures and small fiber axonal function in the obese subjects, most of who were asymptomatic. The findings of the current study are in contrast to the findings in animal models of diet-induced obesity which demonstrated both microvascular and neural dysfunction in nonhyperglycemic animals [24]. These mice develop neuropathy in the absence of hyperglycemia but in presence of hyperlipidemia [25] Non-diabetic mice fed a high-fat diet develop increased levels of oxidized low density lipoproteins, free fatty acids and triglycerides, as well as evidence of increased systemic and nerve oxidative stress.
These mice develop neuropathy in the absence of hyperglycemia [25]. Results of the current study adds substantially to this evolving literature suggesting toxic adiposity and dyslipidemia may be more important contributors to diabetic and idiopathic neuropathy risk than has previously been recognized [25]. Correlation data of the current study assessed the relationship.
Also, previous studies stated that higher BMI is an independent predictor of major renal events in patients with type 2 diabetes.
These findings encourage weight loss to improve nephroprotection in these patients [26,27]. With reference to these findings we can state that high BMI is an independent predictor of DPN.

Study Limitations
The number of patients wishing to participate was too low for a random selection. There was high rates of refusal and dropout from groups. Some patients attended for blood collection without fasting, and some patients refused blood collection by venipuncture because of fear and distress of needles, and hence were excluded from the study. There were also a few patients with other diabetic complications together with neuropathy, and so they were also excluded from the study.

Conclusion
The cost of treating diabetes patients constitutes a large part of the total health care budget, and it is thus important from the economic perspective to have a sound knowledge of the effects of glycemic control , body weight, lipid profile, and Vit D status as different risk factors on diabetic microvascular complications.
In conclusion, our findings suggested Vit D deficiency is an independent risk factor of DPN in T2DM patients.