Effect of Low Level Laser Therapy on serum vitamin D and magnesium levels in patients with diabetic peripheral neuropathy – A pilot study
Diabetes & Metabolic Syndrome: Clinical Research & Reviews, Volume 13, Issue 2, March–April 2019, Pages 1087-1091, https://doi.org/10.1016/j.dsx.2019.01.022
AnjuM.a Lincy Chacko a Yenoshan Chettup allia Arun G.Maiy ab Saleena Ummer Velladath a
- About 12 years ago my wife had very painful lymphedema as a result of therapy following surgery for Breast Cancer
- I read the lymphedema literature and found that LLLT could treat lymphedema.
- It appeared that a flashing infrared light increased the energy in mitochondria
- Big problem however: sets of treatments cost about $1,000 and the devices cost $2,000 - $8,000
- I read the LLLT literature and discovered that I (a retired electronics designer) could design and make one which my wife could use at home.
- The device which I made in 2009 was substantially better than the existing devices ( far fewer treatments needed to get a substantial benefit)
- Note - The literature indicated that the benefit was proportional to the number of light pulses per second
- The LLLT used in the current study used 78 pulses per second, whereas my design has > 5,000 pulses per second
- Note: I designed the LLLT to go > 1" deep, whereas most LLLT are < 1"
- She has been using the LLLT for lymphedema, then her sore ankle, and just this month, her shoulder tendonitis.
- The infrared light produced by my LLLT design is so tiny that I calculated that the resultant heating would be <1% of that needed to be sensed by the lips
- Likewise, my light intensity is so low that I calculated that staring at the LLLT for 1 minute would not be a problem for the eye
- This paper is the first time I became aware that LLLT had any influence on Vitamin D or Magnesium
- I have a design for a second version of the LLLT which would be much easier to assemble and cost < $50 in parts.
- However, I have been spending 60+ hours a week since then on Vitamin D, so have not (yet) looked at making a second version
- Henry Lahore, founder of VitaminDWiki, Feb 2019
- I needed more than Vitamin D to treat my knee osteoarthritis LLLT used by Henry Lahore
- Off topic: Low Level Laser Therapy works - makes Nitric Oxide and ATP has the following chart
40 Type II diabetic patients age 60-70 with peripheral neuropathic pain
Received LLLT treatments on feet for 9 minutes daily for 10 days
Measurements were made 20 days after end of treatment
Huge improvement in VitaminD, Magnesium, ability to sense their feet, and Diabetic Neur. measurement (MNSI)
Pain level 6.8 ==> 1.4
- What is the mechanism for the increases?
Tissues might become better at converting Vitamin D - but why did the Magnesium increase as well?
Does an LLLT-improved Vitamin D production in the tissues somehow not consume as much Magnesium?
- For which other health problems could LLLT increase vitamin D and Magnesium levels?
- Does the LLLT have to be applied at the site of the health problem, or can it be done anywhere?
note: LLLT rarely are able to produce infrared light which goes deeper than about 1 inch
It requires very intense bursts of light with last a very short time (my design uses 10 microsecond duration pulses)
- What other things are also be altered by LLLT?
- How rapidly the Vitamin D and Magnesium start to increase (hours, days?)
- Might there be a dose-dependent relationship between # of minutes of LLLT and increased amount of D or Mg?
- Might the increases be proportional to the number of pulses?
note, my design uses ~90X more pulses per second, and has some off time which seemed important in the literature
- What might result from increasing the duration of each treatment or increasing the number of days of treatment?
- Is there any low-cost real-time indicator that the LLLT treatment is working well?
Blood presssure, heart rate, heart rate variability, arterial wave velocity, Oxygen concentration, brain waves, local blood velocity, local skin temperature, ....?
By the way: LLLT has far more variables than Vitamin D
This is major reason that there are virtually no trials which are comparable
A a few of the variables include
|Pulse length||contant to as short as 1 microsecond|
|Pulse Frequency||constant to 500,000/sec|
|Amplitude|| Constant vs vary with each pulse|
Random, linear, etc
|Duration at a single location on the body||minutes to milliseconds|
|How long until the same locationor same person be treated again||minutes, hours, days?|
|When is the LLLT treatment best done||we found just before going to bed was best|
|"Color" of light used||Single wavelength or multiple|
Other LLLT in VitaminDWiki
- Effectiveness of low level laser therapy for treating male infertility June 2019
Free PDF online,
- Application and development of low-level laser therapy (LLLT) for osteoporosis - Oct 2018,
Behind a paywall https://doi.org/10.1117/12.2501750
- The Nuts and Bolts of Low-level Laser (Light) Therapy - Nov 2011
- LLLT and Headaches
- Efficacy of Low-Level Laser Therapy in the Treatment of Temporomandibular Myofascial Pain: A Systematic Review and Meta-Analysis 2019 Free PDF online
- Low Level Laser Treatment of Tendinopathy: A Systematic Review with Metaanalysis - 2009
Diabetic Peripheral neuropathy (DPN) is the most distressing complication of diabetic population leading to loss of sensation, pain, and amputation. Low-level laser therapy (LLLT) has been used to manage nerve injuries as it holds the potential to induce a biostimulatory effect with no side effects. Hence we planned to study the biochemical effect and therapeutic outcomes of LLLT on patients with painful diabetic peripheral neuropathy as a preliminary work.
Materials and methods
Pre-posttest analysis was done on 40 patients diagnosed with DPN confirmed using 10 g Monofilament test and Michigan Neuropathy Screening Instrument (MNSI). Vibration sensation and pain measured by Vibration perception threshold (VPT) and Numeric pain rating scale (NPRS). All patients were given LLLT (3.1 J/cm2) on plantar and dorsal of the foot for 10 days. Serum samples were collected at baseline and 4 weeks after LLLT to estimate Vitamin D and Magnesium and compared the results.
There was a significant increase in Vitamin D and Magnesium levels after LLLT. We observed a considerable improvement in the quality of life after LLLT demonstrated by a decrease in VPT and MNSI and a reduction in NPRS in DPN patients.
In this study, we found that LLLT improved the QL and hence may be a useful therapeutic option in treating peripheral neuropathic pain in type 2 diabetic patients. The progress in the serum Magnesium and Vit. D levels were proportional to the QL and may be a good indicator of the prognosis of DPN after LLLT.
Anju M1, Lincy Chacko1, Yenoshan Chettupalli1, Arun G Maiya2, Saleena Ummer V 1 1 2
Department of Medical Laboratory Technology, Department of Physiotherapy, School of Allied Health Science, Manipal Academy of Higher Education, Manipal, India
Corresponding author: Dr. Saleena Ummer V Saleena.ummer at manipal.edu
According to the International Diabetes Federation in 2017, approximately 425 million adults are affected with DM globally 1. Long-term association of diabetes leads to microvascular and macrovascular complications due to poor glycemic control2. Long duration of diabetes affects eyes, nerves, kidneys, heart, and feet leading to anatomical, functional, structural changes and multiple organ failure 3. A multicentric study conducted by litwak et al. in diabetes patients reported 27% of macrovascular complication and 37-89% of microvascular complications. Among the microvascular complications, Diabetic Neuropathy had the highest incidence ranging from 25- 83% 4 Young et al. in his study reported a prevalence of diabetic neuropathy as 22.7% in type 1 DM and 32.1 % in type 2 DM. An overall prevalence of neuropathy was reported as 28.5%. Increase in neuropathy was associated with age and duration of DM 5. In India, the prevalence of various complications in diabetes is Cardiovascular (23.6%), Neuropathy (24.6%), Renal (21.1%), Eye (16.6%) and Foot ulcer (5.1%) 6.
Diabetic neuropathy is a group of nerve disorders caused by diabetes including peripheral, autonomic, proximal, and focal, where peripheral neuropathy being the most prevalent (50%)
’ ’ . Diabetic peripheral neuropathy (DPN) is one of the chronic complications of Diabetes Mellitus affecting both somatic and autonomic nervous system. Patients with type 2 diabetes mellitus have a 45% lifetime incidence of neuropathy 10, 11. Most of the patients with DPN suffer from neuropathic pain. When a lesion or dysfunction affects the peripheral nervous system, it leads to Peripheral neuropathic pain 12, 13. It is estimated that 11-32% of DPN patients may present with neuropathic pain. The long-standing peripheral neuropathic pain is seen in one of six diabetic subjects associated with peripheral neuropathy 8. If not taken care properly it leads to foot ulceration and lower extremity amputations. Approximately 15% of people with diabetes have such amputation during their lifetime 14.
DPN is the main initiating factor of foot ulceration and ends up in lower limb amputations associated with more than 50% mortality within five years. An effective means of detecting and treating peripheral neuropathy would have a significant medical, social, and economic impact, as 80% of amputations are preceded by foot ulceration 9. DPN remarkably decreases the quality of life and considerably increases the financial burden of treatment.
Current therapy for painful DPN is aiming for symptomatic relief through various drug administrations. These drugs are often associated with systemic side effects and do not retard the advancement of the underlying neuropathy 15. There are various non-pharmacological management methods used in the treatment of PDNP, like acupuncture, infrared therapy, and various electrotherapies such as spinal cord electrostimulation and transcutaneous electrical nerve stimulation (TENS) 16 Among the electrotherapy modalities, low-level laser therapy (LLLT) is more promising to manage nerve injuries as it holds the potential to induce a biostimulation effect on the nervous system . LLLT uses low intensity light that generates a photochemical effect leading to some biochemical changes within the cell. LLLT uses a power range from 10mW - 500mW at a wavelength ranging from 660 - 905 nm. At low doses, it promotes cell proliferation 18.
Vitamin D deficiency is commonly seen in patient with diabetes. Several studies have reported that intake of Vit D may prevent or delay the onset of diabetes and reduces complications associated 19, 20 Vit. D deficiency is associated with the development of Diabetic peripheral neuropathy. Magnesium is a cofactor for various reactions that need ATP, it is an essential element in cell proliferation and an important factor for immune responses (cellular and humoral) 21, 22. Low serum magnesium is seen in diabetes mellitus 23, 24, 25.
This study aimed to evaluate the effect of LLLT on serum levels of Vit D and Mg+ in patients with DPN.
A prospective Pre-post study was conducted in patients attending diabetic foot clinic, Kasturba hospital, Manipal. After obtaining the ethical clearance from the institutional ethical committee (IEC 786/2016), patients with diabetic peripheral neuropathic pain were recruited into the study after obtaining written informed consent. Patients with diabetic peripheral neuropathic pain with age between 30-70 years were included in the study. Those patients with any other neurological disorder or morbid conditions, DPN with foot ulcer, undergoing chemotherapy and radiation and pregnant women were excluded from the study.
After fulfilling the eligibility criteria, a total of 40 Type II diabetic patients with peripheral neuropathic pain were recruited into the study. A detailed baseline evaluation including tests for neuropathic screening and blood tests were done to confirm the eligibility. Blood tests included Fasting blood sugar and Glycated hemoglobin test that confirmed the DM. The neuropathic testing was done using Michigan Neuropathy Screening Instrument (MNSI), 10g Semmes Weinstein Monofilament and Vibration Perception Threshold (VPT). MNSI contains two separate assessments to assess distal symmetrical DPN. The first part includes 15 self- administered questionnaire and the second part includes brief physical evaluation of lower extremity by examination of foot and assessment of vibration sensation and angle reflexes 26. VPT detects large fiber dysfunction . 10 gm Semmes Weinstein monofilament was used for the detection of loss of protective sensation. Here the Monofilament was applied to the areas on feet perpendicularly by applying a force of 10gm for about one second. If the patient failed to sense the filament after it bends at the test site is taken as considerable loss of sensation. This is considered to be the best method to detect loss of sensation 28, 29. The pain was assessed using numeric pain rating scale.
Baseline Serum samples were collected from all patients. Serum was separated and stored at - 70°C for further analysis of Vit.D and Magnesium.
All subjects included in the study were treated with two separate low level laser, for a period of 10 days. The EC laser of wavelength 632.8 nm with a dosage of 3.1 J/cm2 for 9 minutes was used with scanning mode on the plantar and dorsum of foot and the Thor Laser of wavelengths 660 nm and 850nm with dosage of 3.4 J/cm2 and power density of 50-150 mW/cm2 was used with contact method over popliteal fossa and the neck of fibula for 3 mins and a frequency of 78 Hz.
All participants were reassessed with detailed clinical and biochemical evaluation for serum biomarkers, (Vit.D, Magnesium), Vibration Perception Threshold (VPT), Numeric pain rating scale and MNSI at four weeks after the start of laser intervention to assess the carryover effect of low-level laser therapy.
Both serum samples at baseline and after four weeks of LLLT was collected and stored at -70°C. Serum Magnesium levels were determined by Calmagite Method based on the principle that Magnesium combines with calmagite in an alkaline medium to form red colored complex which is measured colorimetrically at 510nm. 31, 32, 33 Vit.D were estimated by ELISA using quantimicrolisa kit. It is based on competitive ELISA in which samples were diluted with Biotin labeled 25-OH vitamin D conjugate and incubated. Peroxidase labeled streptavidin enzyme conjugate was then added. After incubation and washing steps the substrate was added for color reaction and stopped after a defined time. The color intensity was measured which is inversely proportional to the concentration of 25-OH Vitamin D in the sample.
The data analysis was done using SPSS version 15. Baseline Mean score of VPT, MNSI and Numeric pain rating scale along with mean values of biomarkers were compared with that of 4 weeks after LLLT using Paired t-test. Correlation of biomarkers with NQL was done by Pearson’s correlation coefficient.
A total of 40 patients with diabetic neuropathy with age range of 30-70 yrs. were studied. Among the patient's the majority were males (65%). The duration of Diabetes Mellitus was rangeing from 5-20 yrs. Table 1 shows the demographic characteristic of the patients obtained from the medical records. All patients were using oral glycemic drugs and completed the course of LLLT with no dropout and tolerated laser treatment without any adverse reactions. Mean FBS was 145mg/dl and glycated Hb was 8.1%.
The baseline neuropathic evaluation showed a Median score of MNSI 6.5 and NPRS score from 7. At one month after LLLT the MNSI score showed a median decrease of 3 (p < 0.001) and NPRS score showed a median decrease of 1. This indicate a significant reduction in the pain (p >0.001). The mean baseline VPT value was 39 and there was a significant improvement in the vibration perception (22) after LLLT treatment (p = 0.003).
Out of the total 40 DPN patients 36 were having low levels of serum vitamin D. Hypomagnesemia was observed in 33 patients. There was a significant baseline elevation of both serum Magnesium (p<0.001) and Vit D (p=0.002) in all patients at four weeks after LLLT.
Among the 36 patients with Vit D deficiency, 23 got corrected with the deficiency after LLLT.
Out of 33 with hypomagnesaemia 25 had a rise in Magnesium level after LLLT and reached to normal.
The pre-post changes in biomarkers are shown in Table 2.
Pearson’s correlation analysis revealed a moderate correlation of Vit. D variations with that of MNSI scores after the LLLT (r = 0.5315). Vit. D changes also showed a positive but a weak correlation with that of NPRS (r =0.0097) which is shown in Table 3. But the variations in Magnesium level showed a very weak relationship with that of MNSI and NPRS scores. There was a strong positive correlation of Vit. D with Magnesium levels. We also observed a positive correlation of the baseline variations of these markers (Table 4 & Table 5).
The ROC analysis of baseline variations of Vit. D revealed an AUC of 0.80 (95% CI, 0.66- 0.94) indicating the better performance of Vit. D as a prognostic marker of DPN after LLLT. The baseline variations of Magnesium showed an AUC of 0.62 (95% CI, 0.44 - 0.80) indicating its poor performance. The cut of value for Vit. D variations was found to be 12.5 ng/ml at sensitivity of 77% and specificity of 71%.
The present study used Low Level Laser Therapy modality to investigate its effect on neuropathy pain in type 2 DM. This study holds a higher clinical significance in the management of neuropathic pain in DPN as our results show that LLLT could provide a significant reduction in neuropathic pain that was correlated with increase in biomarker levels. Magnesium deficiency is a proposed factor in the pathogenesis of diabetes-related complications, including neuropathy. In the central nervous system, Mg is also a voltage dependent blocker of N-acetyl -d-aspartate receptor channels involved in the abnormal processing of sensory information 33.
- In this study, there was a significant rise in Magnesium levels after LLLT in DPN patients without any Magnesium supplementation. A recently conducted systematic review and meta-analysis including 1484 type 2 Diabetic patients reported Vitamin D has a significant impact on the of Diabetes mellitus and its associated neuropathy. 39 Vit D deficiency is associated with low neurotrophins which is required for the proper functioning of neurons. A study conducted by Soderstrom et al. in 591 diabetic patients with age above 40 years has been reported that 81% of the patients were having deficiency of Vit D (< 30ng/ml) which was greatly associated with neuropathy.38 We observed a significant elevation of Vit D levels after LLLT with reduction in pain indicated by the decrease in Vibration Perception Threshold (VPT). The reason for the reduction in pain could be attributed to biostimulatory effects of Laser. The study conducted by Kudoh et al. 1989 and Chow et al. 2007 suggested that there could be an increase in nociceptive threshold following a specific dose of LLLT resulting in the neural blockade34, 35. Inhibition of A and C nerve fibers that may be mediated by neural enzyme inhibition that also could play a significant role in pain inhibition.
In addition it has been suggested that LLLT would lead to increased endorphin production 36 and nitric oxide that contribute for better healing 37 The findings from the present study demonstrate that LLLT was effective in showing its positive effects on Vit. D and Magnesium levels to manage neuropathic pain in diabetic patients. One of the limitations of this study is that most of the patients are between 60 to 70 years old, inclusion of age groups with uniform distribution between 30-70 years could have been more significant. The results of this study are encouraging in terms of alternative therapy for DPN with a lower risk of side effects. Hence we recommend that a larger sample sized randomized control trials should be conducted to confirm our findings and identify further applicability.
The reduction in neuropathic pain was associated with the increase in serum Vit. D and Magnesium levels after four weeks which may be a good indicator of the role of LLLT in neurodegeneration. Further studies on surrogate markers may give new insights into the mechanism of action of Laser which may open the door to identify the most suitable marker for monitoring the therapy.
Funding: This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
Acknowledgements: Authors would like to thank Centre for Diabetic Foot Care and Research, Manipal Academy of Higher Education.
Declaration of interest: The authors report no conflicts of interest.
- International Diabetes Federation. IDF Diabetes Atlas, 8th edn Brussels, Belgium: International Diabetes Federation, 2017.
- Nathan DM. Long-term complications of diabetes mellitus. New England Journal of Medicine. 1993 Jun 10;328(23):1676-85.
- Rahman S, Rahman T, Ismail AA, Rashid AR. Diabetes-associated macrovasculopathy: pathophysiology and pathogenesis. Diabetes, Obesity and Metabolism. 2007 Nov 1;9(6):767-80.
- Litwak L, Goh SY, Hussein Z, Malek R, Prusty V, Khamseh ME. Prevalence of diabetes complications in people with type 2 diabetes mellitus and its association with baseline characteristics in the multinational A 1 chieve study. Diabetology & metabolic syndrome. 2013 Oct 24;5(1):57.
- Young MJ, Boulton AJ, MacLeod AF, Williams DR, Sonksen PH. A multicentre study of the prevalence of diabetic peripheral neuropathy in the United Kingdom hospital clinic population. Diabetologia. 1993 Feb 1;36(2):150-4.
- Mohan V, Shah S, Saboo B. Current glycemic status and diabetes related complications among type 2 diabetes patients in India: data from the A1chieve study. The Journal of the Association of Physicians of India. 2013;61(1 Suppl): 12-5.
- Barrett AM, Lucero MA, Le T, Robinson RL, Dworkin RH, Chappell AS. Epidemiology, public health burden, and treatment of diabetic peripheral neuropathic pain: a review. Pain medicine. 2007 Sep 1;8(s2).
- Boulton AJ. Management of diabetic peripheral neuropathy. Clinical diabetes. 2005 Jan 1;23(1):9-15.
- Kruse I, Edelman S. Evaluation and treatment of diabetic foot ulcers. Clinical diabetes. 2006 Apr 1;24(2):91-3.
- Russell JW, Zilliox LA. Diabetic neuropathies. Continuum: Lifelong Learning in Neurology. 2014 Oct;20(5 Peripheral Nervous System Disorders): 1226.
- Zilliox L, Russell JW. Treatment of diabetic sensory polyneuropathy. Current treatment options in neurology. 2011 Apr 1; 13(2): 143-59.
- Karri Vn. Current Perspective In The Management Of Diabetic Foot Ulcers-An Overview On The Indian Scenario. Clinical Trials. 2012;22:287-93.
- Pham H, Armstrong DG, Harvey C, Harkless LB, Giurini JM, Veves A. Screening techniques to identify people at high risk for diabetic foot ulceration: a prospective multicenter trial. Diabetes care. 2000 May 1;23(5):606-11.
- Deshpande AD, Harris-Hayes M, Schootman M. Epidemiology of diabetes and diabetes- related complications. Physical therapy. 2008 Nov 1;88(11):1254-64.
- Javed S, Petropoulos IN, Alam U, Malik RA. Treatment of painful diabetic neuropathy. Therapeutic advances in chronic disease. 2015 Jan;6(1):15-28.
- Bailey A, Wingard D, Allison M, Summers P, Calac D. Acupuncture Treatment of Diabetic Peripheral Neuropathy in an American Indian Community. Journal of acupuncture and meridian studies. 2017 Apr 1;10(2):90-5.
- Yamany AA, Sayed HM. Effect of low level laser therapy on neurovascular function of diabetic peripheral neuropathy. Journal of Advanced Research. 2012 Jan 31;3(1):21-8.
- Cotler HB, Chow RT, Hamblin MR, Carroll J. The use of low level laser therapy (LLLT) for musculoskeletal pain. MOJ orthopedics & rheumatology. 2015;2(5).
- Pittas AG, Dawson-Hughes B, Li T, Van Dam RM, Willett WC, Manson JE, Hu FB. Vitamin D and calcium intake in relation to type 2 diabetes in women. Diabetes care. 2006 Mar 1;29(3):650-6.
- Soderstrom LH, Johnson SP, Diaz VA, Mainous AG. Association between vitamin D and diabetic neuropathy in a nationally representative sample: results from 2001-2004 NHANES. Diabetic medicine. 2012 Jan 1;29(1):50-5.
- Tosiello L. Hypomagnesemia and diabetes mellitus. Arch Intern Med. 1996 Jun 10;156(11):1143-8.
- White Jr JR, Campbell RK. Magnesium and diabetes: a review. Annals of Pharmacotherapy. 1993 Jun;27(6):775-80.
- Sales CH, Pedrosa LD. Magnesium and diabetes mellitus: their relation. Clinical Nutrition. 2006 Aug 1;25(4):554-62.
- Dong JY, Xun P, He K, Qin LQ. Magnesium intake and risk of type 2 diabetes: metaanalysis of prospective cohort studies. Diabetes care. 2011 Sep 1;34(9):2116-22.
- Arpaci D, Tocoglu AG, Ergenc H, Korkmaz S, Ucar A, Tamer A. Associations of serum Magnesium levels with diabetes mellitus and diabetic complications. Hippokratia. 2015 Apr;19(2):153.
- Feldman EL, Stevens MJ, Thomas PK, Brown MB, Canal N, Greene DA. A practical two-step quantitative clinical and electrophysiological assessment for the diagnosis and staging of diabetic neuropathy. Diabetes care. 1994 Nov 1;17(11): 1281-9.
- Boulton AJ, Vinik AI, Arezzo JC, Bril V, Feldman EL, Freeman R, Malik RA, Maser RE, Sosenko JM, Ziegler D. Diabetic neuropathies: a statement by the American Diabetes Association. Diabetes care. 2005 Apr 1;28(4):956-62.
- Abbott CA, Carrington AL, Ashe H, Bath S, Every LC, Griffiths J, Hann AW, Hussein A, Jackson N, Johnson KE, Ryder CH. The North-West Diabetes Foot Care Study: incidence of, and risk factors for, new diabetic foot ulceration in a community-based patient cohort. Diabetic Medicine. 2002 May 1;19(5):377-84.
- McGill M, Molyneaux L, Yue DK. Use of the Semmes-Weinstein 5.07/10 gram monofilament: the long and the short of it. Diabetic medicine. 1998 Jul 1;15(7):615-7.
- Ryan MF, Barbour H. Magnesium measurement in routine clinical practice. Annals of clinical biochemistry. 1998 Jul;35(4):449-59.
- Elin RJ. Determination of serum magnesium concentration by clinical laboratories. Magnesium and trace elements. 1991;10(2-4):60-6.
- Chauhan UP, Sarkar BR. Use of calmagite for the determination of traces of magnesium in biological materials. Analytical biochemistry. 1969 Oct 1;32(1):70-80.
- Rondon LJ, Privat AM, Daulhac L, Davin N, Mazur A, Fialip J, Eschalier A, Courteix C. Magnesium attenuates chronic hypersensitivity and spinal cord NMDA receptor phosphorylation in a rat model of diabetic neuropathic pain. The Journal of physiology. 2010 Nov 1;588(21):4205-15.
- Kudoh C, Inomata K, Okajima K, Motegi M, Ohshiro T. Histochemical and biochemical effects of 830nm gallium aluminium arsenide diode laser radiation on rat saphenous nerve Na-K-ATPase activity. Low Level Laser Therapy. 1989;1:27.
- Chow RT, David MA, Armati PJ. 830 nm laser irradiation induces varicosity formation, reduces mitochondrial membrane potential and blocks fast axonal flow in small and medium diameter rat dorsal root ganglion neurons: implications for the analgesic effects of 830 nm laser. Journal of the Peripheral Nervous System. 2007 Mar 1;12(1):28-39.
- Yamamoto H. Antinociceptive effects of laser irradiation of Hoku point in rats. Pain Clin. 1988;8:43-8.
- Cidral-Filho FJ, Mazzardo-Martins L, Martins DF, Santos AR. Light-emitting diode therapy induces analgesia in a mouse model of postoperative pain through activation of peripheral opioid receptors and the L-arginine/nitric oxide pathway. Lasers in medical science. 2014 Mar 1;29(2):695-702.
- Soderstrom LH, Johnson SP, Diaz VA, Mainous Iii AG. Association between vitamin D and diabetic neuropathy in a nationally representative sample: results from 2001-2004 NHANES. Diabetic medicine. 2012 Jan;29(1):50-5.
- Lv WS, Zhao WJ, Gong SL, Fang DD, Wang B, Fu ZJ, Yan SL, Wang YG. Serum 25- hydroxyvitamin D levels and peripheral neuropathy in patients with type 2 diabetes: a systematic review and meta-analysis. Journal of endocrinological investigation. 2015 May 1 ;38(5): 513-8.