Diabetic neuropathy and microcirculation

Conjunctival microcirculation in ocular and systemic microvascular disease

The conjunctival microcirculation is an accessible complex network of micro vessels whose quantitative assessment can reveal microvascular haemodynamic properties. Currently, algorithms for the measurement of conjunctival haemodynamics use either manual or semi-automated systems, which may provide insight into overall conjunctival health, as well as in ocular and systemic disease. These algorithms include functional slit-lamp biomicroscopy, laser doppler flowmetry, optical coherence tomography angiography, orthogonal polarized spectral imaging, computer-assisted intravitral microscopy, diffuse reflectance spectroscopy and corneal confocal microscopy. Furthermore, several studies have demonstrated a relationship between conjunctival microcirculatory haemodynamics and many diseases such as dry eye disease, Alzheimer's disease, diabetes, hypertension, sepsis, coronary microvascular disease, and sickle cell anaemia. This review aims to describe conjunctival microcirculation, its characteristics, and techniques for its measurement, as well as the association between conjunctival microcirculation and microvascular abnormalities in disease states.

Disparity in association of obesity measures with ankle and brachial systolic blood pressures in Europeans and South Asians

Obesity causes increases in brachial systolic-blood-pressures (SBP), risks of type 2 diabetes (T2DM) and cardiovascular diseases (CVD). Brachial and ankle SBPs have differential relationship with T2DM and CVD. Our objective was to study the relationship of obesity measures with brachial and ankle SBPs. A population of 1098 adults (South Asians n = 699; 41.70% male and 58.3% female) were recruited over 5 years from primary care practices in England. Their four limbs SBPs were measured using Doppler machine and body-mass-index (BMI) and waist-to-height-ratio (WHtR) calculated. Linear regressions were performed between SBPs and obesity measures, after adjustments for sex, age, ethnicity, T2DM and CVD. The mean age of all participants was 51.3 (SD = 17.2), European was 57.7 (SD 17.2) and South Asian was 47.8 (SD = 16.1). The left posterior tibial [Beta = 1.179, P = 4.559 × 10⁻¹⁵] and the right posterior tibial SBP [Beta = 1.178, P = 1.114 × 10⁻¹³] most significantly associated with the BMI. In South Asians, although the left brachial [Beta = 25.775, P = 0.032] and right brachial SBP [Beta = 22.792, P = 0.045] were associated to the WHtR, the left posterior tibial SBP [Beta = 39.894, P = 0.023], association was the strongest. For the first time, we have demonstrated that ankle SBPs had significant association with generalised obesity than brachial systolic blood pressures (SBP), irrespective of ethnicity. However, with respect to visceral obesity, the association with ankle SBP was more significant in South Asians compared to Europeans.

Fibrinogen function indexes are potential biomarkers of diabetic peripheral neuropathy

BACKGROUND AND OBJECTIVES

Research suggests that diabetic peripheral neuropathy (DPN) is related to plasma fibrinogen (Fib) concentrations, although its correlation with Fib function has not been reported. Here, the k value and angle α, reflecting the plasma Fib function, were used to analyse its correlation with DPN, and their potential as biological indicators for diagnosing DPN was explored.

SUBJECTS AND METHODS

This prospective observational clinical study enrolled 561 type 2 diabetes mellitus (T2DM) patients, who were divided into the diabetes with symptomatic neuropathy (161 cases), diabetes with asymptomatic neuropathy (132 cases) and diabetes with no neuropathy (268 cases) groups. Meanwhile, 160 healthy unrelated subjects were recruited as controls.

RESULTS

Fib levels increased slightly in diabetic subjects with neuropathy compared with those without. The angle α levels increased slightly in subjects with asymptomatic DPN compared with those with no neuropathy and increased greatly in subjects with symptomatic DPN compared with those without. The k value levels slightly decreased in subjects with asymptomatic DPN compared with those with no neuropathy and greatly decreased in subjects with symptomatic DPN compared with those without. The association of the k value and angle α with diabetic neuropathy was independent of the hyperglycaemic state and other potential confounders (odds ratio 0.080 [0.051-0.124], P < 0.001; odds ratio 1.131 [1.063-1.204], P < 0.001). The k value and angle α levels were closely correlated with neuropathy stage (r  = - 0.686, P < 0.000; r  = 0.314, P < 0.001). The optimal cut-off point for k value levels to distinguish patients with diabetic neuropathy from those without was 1.8 min, with a sensitivity of 73.7% and a specificity of 83.2% (AUC = 0.873). The optimal cut-off point for angle α levels was 60°, with a sensitivity of 41.0% and a specificity of 95.6% (AUC = 0.669).

CONCLUSIONS

The k value and angle α are closely associated with DPN. The levels of the k value and angle α may be helpful in the early diagnosis of DPN.

Herbal Oils for Treatment of Chronic and Diabetic Wounds: A Systematic Review

BACKGROUND

In the present scenario, diabetes is a growing health challenge, and its occurrence is growing across the globe. Diabetes, with its complications like diabetic wounds, vasculopathy, neuropathy, wound infections, and oxidative stress, is a serious cause of mortality worldwide.

INTRODUCTION

Among the various complications, treatment of diabetic foot and ulcers is one of the major concerns in patients who are suffering from diabetes. The causative factors for this condition include increased oxidative stress, high blood glucose levels, vascular insufficiency, and microbial infections, and many a time, if left untreated, it may even lead to amputations of the lower extremities. The present therapy for the treatment of diabetic wounds mainly involves the use of synthetic moieties and other biotechnology-derived biomolecules, including growth factors. Few plant products are also useful in the treatment of wounds.

METHODS

Essential oils derived from various herbs are reported to possess significant wound healing potential and promote blood clotting, help to fight infections, and accelerate the wound healing process. Hence, the present review is a systematic analysis of all the available data on the use of the natural oils with their biological source, active phytochemical constituents present, and the probable mechanism of action for the treatment of chronic and diabetic wounds in suitable animal models. A methodical collection of data was performed, and information was searched up to April 2020 in entirety. Key phrases used for the data search include the pathophysiology of wounds, diabetic foot wound and its complications, natural oils for chronic and diabetic wound treatment.

RESULTS

This review summarizes the natural oils which are reported in the literature to be beneficial in the treatment of chronic wounds, while some oils have been specifically also studied against wounds in diabetic rats. Essential oils are said to interact with the body pharmacologically, physiologically and psychologically and help in rapid wound healing. However, the majority of the literature studies have demonstrated wound healing activity only in animal models (preclinical data), and further clinical studies are necessary.

CONCLUSION

This review provides a platform for further studies on the effective utilization of natural oils in the treatment of chronic and diabetic wounds, especially if oils are to receive credibility in the management of chronic wounds.

Impaired Vascular Endothelial Function is Associated with Peripheral Neuropathy in Patients with Type 2 Diabetes

PURPOSE

It is believed that vascular endothelial dysfunction is involved in the occurrence of cardiovascular disease (CVD), and diabetic peripheral neuropathy (DPN) is associated with flow-mediated dilation (FMD), however, the correlation is still unclear. Aims of the present study is to explore the relationship between DPN parameters and FMD, providing a new approach for the prevention of CVD.

PATIENTS AND METHODS

A total of 272 patients with T2DM from the Department of Endocrinology of The First Hospital of Lanzhou University according to the grading criteria were selected. FMD was measured by a new vascular ultrasound system and patients were divided into FMD>7%, 4%≤FMD≤7%, and FMD<4% groups. The Toronto Clinical Scoring System (TCSS) was used to assess the severity of DPN. The nerve conduction studies (NCS) assessed large fibre neuropathy by nerve conduction velocity (CV), compound muscle action potential (CMAP) amplitude (Amp), and distal motor latency (DML). SPSS 25.0 was used for statistical analysis.

RESULTS

TCSS evaluation revealed that the percentage of patients with severe nerve injury was significantly higher in FMD<4% (70%) compared to FMD>7% (2%). Among the TCSS indicators of all subjects, the proportion of temperature disturbance was the most (73%), and joint position disturbance was the least (0). TCSS scores were negatively correlated with FMD (r=-0.756, p<0.001). More interesting, in FMD<4% group, CV and Amp were positively correlated with FMD, while DML was negatively correlated (p<0.05). Linear regression analysis model showed that different systolic blood pressure (SBP), triglyceride (TG), TCSS and CV had statistically different effects on FMD.

CONCLUSION

High TCSS score and decreased CV of common peroneal and tibial nerves are risk factors of FMD injury, which provide potential value for timely prevention and treatment of cardiovascular diseases.

Inter-ankle Systolic Blood Pressure Difference Is a Marker of Increased Fasting Blood-Glucose in Asian Pregnant Women

OBJECTIVE

This cross-sectional study aimed to determine the relationship between clinical blood pressures and blood pressures measured using Doppler with blood glucose in pregnancy by ethnicity.

METHODS

We recruited 179 (52% White European, 48% Asian) pregnant women at 24-28 weeks of gestation who underwent a glucose tolerance test in an antenatal clinic in Bradford Royal Infirmary, the UK, from 2012 to 2013. Systolic blood pressures in the arm (left and right brachial) and ankle [left and right posterior tibial (PT) and dorsalis pedalis (DP)] blood pressures were measured using a Doppler probe. The inter-arm (brachial) and inter-ankle (PT and DP) systolic blood pressure differences were obtained. A multivariate linear regression model adjusted for age, body mass index, and diabetes risk was used to assess the relationship between blood pressures and blood glucose.

RESULTS

Asian pregnant women had higher blood glucose but lower ankle blood pressures than White Europeans. In White Europeans, brachial blood pressures and clinical blood pressures were positively associated with fasting blood glucose (FBG), but brachial blood pressures did not perform better as an indicator of FBG than clinical blood pressures. In Asians, increased inter-ankle blood pressure difference was associated with increased FBG. For each 10 mmHg increase in the inter-ankle blood pressure difference, FBG increased by 0.12 mmol/L (Beta=0.12, 95%CI: 0.01-0.23).

CONCLUSION

The relationship between blood pressures with blood glucose differed by ethnicity. In Asians, inter-ankle systolic blood pressure difference was positively associated with blood glucose. This is first ever report on ankle blood pressures with blood glucose in pregnancy which suggests future potential as a non-invasive gestational diabetes risk screening tool.

Microvascular rarefaction in patients with cerebrovascular events

Capillary density rarefaction and endothelial dysfunction contribute to chronic hypoperfusion and cerebral small vessel disease. Previous animal experiments revealed spatiotemporal microvascular remodeling directing post-stroke brain reorganization. We hypothesized that microcirculatory changes during acute cerebrovascular events could be reflected systemically and visualized sublingually. In a prospective observational trial in vivo sublingual sidestream darkfield videomicroscopy was performed in twenty-one patients with either acute stroke (n = 13 ischemic, n = 1 ischemic with hemorrhagic transformation and n = 2 hemorrhagic stroke) or transitory ischemic attacks (n = 5) within 24 h after hospital admission and compared to an age- and sex-matched control group. Repetitive measurements were performed on the third day and after one week. Functional and perfused total capillary density was rarefied in the overall patient group (3060 vs 3717 μm/mm², p = 0.001 and 5263 vs 6550 μm/mm², p = 0.002, respectively) and in patients with ischemic strokes (2897 vs. 3717 μm/mm², p < 0.001 and 5263 vs. 6550 μm/mm², p = 0.006, respectively) when compared to healthy controls. The perfused boundary region (PBR), which was measured as an inverse indicator of glycocalyx thickness, was markedly related to red blood cell (RBC) filling percentage (regarded as an estimate of microvessel perfusion) in the overall patient group (r = -0.843, p < 0.001), in patients with ischemic strokes (r = -0.82, p = 0.001) as well as in healthy volunteers (r = -0.845, p < 0.001). In addition, there were significant associations between platelet count or platelet aggregation values (as measured by whole blood impedance aggregometry) and microvascular parameters in the overall patient collective, as well as in patients with ischemic strokes. In conclusion, cerebrovascular events are associated with altered systemic microvascular perfusion.

The Role of Cutaneous Microcirculatory Responses in Tissue Injury, Inflammation and Repair at the Foot in Diabetes

Diabetic foot syndrome is one of the most costly complications of diabetes. Damage to the soft tissue structure is one of the primary causes of diabetic foot ulcers and most of the current literature focuses on factors such as neuropathy and excessive load. Although the role of blood supply has been reported in the context of macro-circulation, soft tissue damage and its healing in the context of skin microcirculation have not been adequately investigated. Previous research suggested that certain microcirculatory responses protect the skin and their impairment may contribute to increased risk for occlusive and ischemic injuries to the foot. The purpose of this narrative review was to explore and establish the possible link between impairment in skin perfusion and the chain of events that leads to ulceration, considering the interaction with other more established ulceration factors. This review highlights some of the key skin microcirculatory functions in response to various stimuli. The microcirculatory responses observed in the form of altered skin blood flow are divided into three categories based on the type of stimuli including occlusion, pressure and temperature. Studies on the three categories were reviewed including: the microcirculatory response to occlusive ischemia or Post-Occlusive Reactive Hyperaemia (PORH); the microcirculatory response to locally applied pressure such as Pressure-Induced Vasodilation (PIV); and the interplay between microcirculation and skin temperature and the microcirculatory responses to thermal stimuli such as reduced/increased blood flow due to cooling/heating. This review highlights how microcirculatory responses protect the skin and the plantar soft tissues and their plausible dysfunction in people with diabetes. Whilst discussing the link between impairment in skin perfusion as a result of altered microcirculatory response, the review describes the chain of events that leads to ulceration. A thorough understanding of the microcirculatory function and its impaired reactive mechanisms is provided, which allows an understanding of the interaction between functional disturbances of microcirculation and other more established factors for foot ulceration.

Differential associations of ankle and brachial blood pressures with diabetes and cardiovascular diseases: cross-sectional study

Increased brachial systolic blood-pressure (BP) predicts diabetes (T2DM) but is not fully effective. Value of absolute ankle systolic BP for T2DM compared to brachial systolic BP is not known. Our objectives were to assess independent relationships of ankle-systolic BP with T2DM and cardiovascular disease in Europeans and south Asians. Cross-sectional studies of anonymised data from registered adults (n = 1087) at inner city deprived primary care practices. Study includes 63.85% ethnic minority. Systolic BP of the left and right-brachial, posterior-tibial and dorsalis-pedis-arteries measured using a Doppler probe. Regression models' factors were age, sex, ethnicity, body mass index (BMI) and waist height ratio (WHtR). Both brachial and ankle systolic-BP increase with diabetes in Europeans and south Asians. We demonstrated that there was a significant positive independent association of ankle BP with diabetes, regardless of age and sex compared to Brachial. There was stronger negative association of ankle blood pressure with cardiovascular disease, after adjustment for BMI, WHtR and ethnicity. Additionally, we found that ankle BP were significantly associated with cardiovascular disease in south Asians more than the Europeans; right posterior tibial. Ankle systolic BPs are superior to brachial BPs to identify risks of Type 2DM and cardiovascular diseases for enhanced patient care.

A walking bout reveals altered foot thermodynamics associated with unilateral transtibial amputation among individuals with type 2 diabetes

BACKGROUND

Increased foot temperature among individuals with type 2 diabetes can be predictive of diabetic foot ulcer development. A combination of physiological and mechanical deficiencies may contribute to elevations in intact foot temperature during gait for individuals with type 2 diabetes and transtibial amputation.

OBJECTIVE

This study evaluated plantar foot temperature differences between individuals with type 2 diabetes with and without transtibial amputation. We hypothesized that individuals with transtibial amputation maintain increased foot temperature compared to those without amputation.

STUDY DESIGN

Cross-sectional, case control.

METHODS

A sample of 16 participants with type 2 diabetes and transtibial amputation, and 16 age- and sex-matched participants with type 2 diabetes without amputation were recruited. Foot temperatures were measured during resting, walking, and cooldown periods. Peak temperature, mean temperature, and rate of temperature change were analyzed for each period, and compared between cohorts.

RESULTS

Participants with amputation exhibited increased mean foot temperature while at rest and during walking. Participants without amputation exhibited increased rate of change of foot temperature during walking. No differences in peak temperature or rate of temperature change were observed during the baseline or cooldown periods.

CONCLUSION

The current findings of altered foot temperature for individuals with transtibial amputation and type 2 diabetes suggest a possible reason for the high rates of contralateral limb ulceration and amputation among this population.

Degree of adiposity and obesity severity is associated with cutaneous microvascular dysfunction in type 2 diabetes

BACKGROUNDS AND AIMS

Obesity and diabetes independently contribute to cutaneous microvascular dysfunction via pathological processes that are not fully understood. We sought to determine if obesity severity is associated with cutaneous microvascular dysfunction and measures of peripheral arterial disease in adults with type 2 diabetes in cross-sectional observational study design.

METHODS AND RESULTS

Primary outcomes were post-occlusive reactive hyperaemia as determined by laser-Doppler fluxmetry (peak flux post-occlusion, time to peak flux post-occlusion, peak as a percentage of baseline, and area under the curve [AuC] index post-occlusion to pre-occlusion). Secondary outcomes were ankle- and toe-brachial indices (ABI and TBI) and systolic toe pressure. Thirty-six participants (20 men, 16 women) with mean age 55 ± 8 years, BMI of 36 ± 5 kg/m² and duration of diabetes 8 ± 6 years underwent measurements. After adjusting for age and duration of diabetes, SAT and total percentage body fat were able to explain 29% (p = 0.001) and 20% (p = 0.01) of variance of AuC index models, as well as 29% (p = 0.02) and 18% (p = 0.02) of peak as a percentage of baseline models, respectively. Though TBI demonstrated moderate, significant correlations with SAT (r:0.37, p = 0.04) and total percentage body fat (r:0.39, p = 0.03), these were not upheld by regression analyses. Neither ABI nor systolic toe pressure significantly correlated with any measure of adiposity or obesity.

CONCLUSION

These findings demonstrate impairment in cutaneous microvascular function related to adiposity and obesity severity in adults with type 2 diabetes, suggesting that obesity may pathologically effect cutaneous microvascular function in the absence of overt macrovascular disease, warranting further investigation.

Videocapillaroscopy of the Oral Mucosa in Patients with Diabetic Foot: Possible Diagnostic Role of Microangiopathic Damage?

INTRODUCTION

Diabetic foot represents one of the most serious and expensive complications of diabetes and is subject to a high percentage of amputations that are almost always preceded by ulcers ascribable to neuropathy and/or vasculopathy. Videocapillaroscopy (VCS) can be a valuable aid in order to uncover morpho-structural anomalies in the vascular bed, both at the level of the oral mucosa and at the level of the terminal vessels of the lower limb.

MATERIALS AND METHODS

Sixty subjects divided into 4 groups were enrolled: 15 healthy subjects; 15 patients with diabetes for more than 10 years without ulcerative foot lesions; 15 patients with neuropathic diabetic foot (clinical diagnosis, MDNS); 15 patients with ischemic diabetic foot (clinical diagnosis, ABI, lower limb doppler). A complete videocapillaroscopic mapping of the oral mucosa was carried out on each patient. The areas investigated were: labial mucosa, the retro-commissural region of the buccal mucosa, and the vestibular masticatory mucosa (II and V sextant).

RESULTS

The analysis of the morphological and densitometric characteristics of the capillaries revealed the following: a significant reduction in capillary density in neuropathic (mean ± SD 7.32 ± 2.1) and ischemic patients (mean ± SD 4.32 ± 3.2) compared to the control group of patients (both diabetic mean ± SD 12.98 ± 3.1 and healthy mean ± SD 19.04 ± 3.16) (ANOVA test and Bonferroni t test p < 0.05); a reduction in the average length of the capillaries and a significant increase in tortuosity (ANOVA test and Bonferroni t test p < 0.05). In the neuropathic patients, a recurrent capillaroscopic pattern that we defined as "sun" was found, with capillaries arranged radially around an avascular area.

CONCLUSIONS

The data obtained from this preliminary study suggest a potential diagnostic role of oral capillaroscopy in the early and subclinical identification of microangiopathic damage in patients with diabetic foot.

Type II Diabetes Patients under Sildenafil Citrate: Case Series Showing Benefits and a Side Effect

Background

Diabetes mellitus is a highly prevalent disease with rapid universal growth. In 2013, there were already 382 million people with diabetes, and it is expected that by 2035, this number will double. Chronic hyperglycemia causes a series of biochemical and structural changes, especially in the eyes, kidneys, heart, arteries, and peripheral nerves, which usually leads to the progression of microvascular disease. Several literature reports showed that the chronic use of phosphodiesterase-5 inhibitors enhances the insulin sensitivity, improves the markers of endothelial function, and helps in the treatment of severe extremity ischemia and pulmonary hypertension. We aim to test the effect of sildenafil citrate (SC) as a glucose and microcirculation regulator in diabetic patients, paying special attention to the consequences of its use in the regulation of blood glucose level. Case Presentation. Two male patients, aged 53 and 73 years, with type II diabetes, using oral hypoglycemic agents and presenting pathology associated with microcirculation alterations and ischemia, were medicated daily with SC. Both patients presented a reduction in the glycemic level, requiring lower doses or no other oral diabetes medications. Patient 1, who presented diabetic foot, was treated in the ambulatory, and patient 2, with chronic obstructive pulmonary disease and consequent mild pulmonary hypertension, was treated in the office. In addition to the clinical improvement of foot wounds and dyspnea due to the increase in microcirculatory perfusion, hypoglycemic episodes were observed in both patients under SC. The patient with pulmonary hypertension experienced one severe hypoglycemia episode and had to be taken to an emergency room.

Conclusion

Type 2 diabetic patients may benefit from the use of a phosphodiesterase-5 inhibitor in order to improve the microcirculatory perfusion as well as glycemic control. However, adverse side effects may involve hypoglycemia. Since off-label use of SC in patients suffering from microcirculatory alterations has increased recently, our results showed that more studies are needed to verify the prevalence of hypoglycemia episodes as well as it's possible physiologic mechanism.

The Impact of Extracorporeal Shock Wave Therapy on Microcirculation in Diabetic Feet: A Pilot Study

BACKGROUND

Patients with diabetic foot commonly experience vascular insufficiency and compromised tissue perfusion. Extracorporeal shockwave therapy (ESWT) reportedly promotes wound healing and angiogenesis, but clinical studies on the effect of ESWT on angiogenesis are scarce and the exact mechanism remains unclear.

OBJECTIVE

To investigate the effect of ESWT on cutaneous microcirculation in diabetic feet.

METHODS

Ten patients with diabetic feet received ESWT twice weekly for a total of six sessions. Transcutaneous partial oxygen pressure (TcPO2) and cutaneous blood flow were measured before and after ESWT.

MAIN RESULTS

The treated feet showed statistically significant improvements in the mean TcPO2 (P < .01) and cutaneous blood flow level (P < .05) compared with control feet. In treated feet, TcPO2 increased by 19.6%, from 41.4 ± 9.9 to 49.5 ± 8.7 mm Hg (P < .05). In control feet, TcPO2 decreased by 11.6%, from 39.5 ± 14.0 to 34.9 ± 14.5 mm Hg (P = .059). The average cutaneous blood flow level of treated feet before ESWT was 36.9 ± 25.6, which increased to 48.3 ± 32.4 AU after ESWT (30.9% increase; P = .646). In control feet, the cutaneous blood flow level decreased from 80.5 ± 36.7 to 60.4 ± 38.8 AU, a decrease of 25.0% (P = .241).

CONCLUSIONS

These results demonstrate that ESWT may have beneficial effects on microcirculation in diabetic feet.

Characterizing Vascular Dysfunction in Genetically Modified Mice through the Hyperoxia Model

Modelling is essential for a better understanding of microcirculatory pathophysiology. In this study we tested our hyperoxia-mouse model with healthy and non-healthy mice. Animals (n = 41) were divided in groups—a control group, with 8 C57/BL6 non-transgenic male mice, a diabetic group (DB), with 8 C57BLKsJ-db/db obese diabetic mice and the corresponding internal controls of 8 age-matched C57BLKsJ-db/+ mice, and a cardiac hypertrophy group (CH), with 9 FVB/NJ cα-MHC-NHE-1 transgenic mice prone to develop cardiac failure and 8 age-matched internal controls. After anesthesia, perfusion data was collected by laser Doppler flowmetry (LDF) during rest (Phase 1), hyperoxia (Phase 2), and recovery (Phase 3) and compared. The LDF wavelet transform components analysis (WA) has shown that cardiorespiratory, myogenic, and endothelial components acted as main markers. In DB group, db/+ animals behave as the Control group, but WA already demonstrated significant differences for myogenic and endothelial components. Noteworthy was the increase of the sympathetic components in the db/db set, as in the cardiac overexpressing NHE1 transgenic animals, reported as a main component of these pathophysiological processes. Our model confirms that flow motion has a universal nature. The LDF component’s WA provides a deeper look into vascular pathophysiology reinforcing the model’s reproducibility, robustness, and discriminative capacities.

Consistency of Toe Systolic Pressures, Brachial Systolic Pressures, and Toe-Brachial Indices in People with and without Diabetes

BACKGROUND & AIMS

Toe Systolic Blood Pressures (TSPs) and Toe-Brachial Indices (TBIs) have been identified as useful adjuncts in the identification of pedal ischemia, peripheral artery occlusive diseases, and risk for either nonhealing of lower extremity wounds or for amputation. Valid measurement of TSPs and TBIs is therefore essential. However, it could be jeopardized by rater, instrument, and intratestee inconsistency. These three sources of inconsistency were examined in this research.

METHODS

Five publications addressing TSP and TBI consistency were identified and their results were analyzed using intraclass correlation coefficients.

RESULTS

Moderate variability in TSPs was found across all studies; greater variability was evidenced in brachial systolic pressure, particularly for people who had diabetes; and TBI values also exhibited considerable variability, but little difference between people who did and did not have diabetes.

CONCLUSION

These findings provide qualified evidence of consistency regarding measurement of TSPs but challenge TBI as a valid and useful indicator in screening, prognostic, and monitoring contexts, particularly for people who have diabetes. However, there is a prospect that TBI assessment could be improved by adherence to standardized protocols and by obtaining multiple measurements from toes and arms on a single occasion as well as on different occasions.

Influence of Negative-Pressure Wound Therapy on Tissue Oxygenation in Diabetic Feet

OBJECTIVE

Negative-pressure wound therapy (NPWT) has become a common wound care treatment modality for a variety of wounds. Several previous studies have reported that NPWT increases blood flow in the wound bed. However, NPWT might decrease tissue oxygenation in the wound bed because the foam sponge of NPWT compresses the wound bed under the influence of the applied negative pressure. Adequate tissue oxygenation is an essential consideration during diabetic foot management, and the foot is more sensitive to ischemia than any other region. Furthermore, the issue as to whether NPWT reduces or increases tissue oxygenation in diabetic feet has never been correctly addressed. The aim of this study was to evaluate the influence of NPWT on tissue oxygenation in diabetic feet.

PARTICIPANTS

Transcutaneous partial oxygen pressures (TcPO2) were measured to determine tissue oxygenation levels beneath NPWT dressings on 21 feet of 21 diabetic foot ulcer patients.

DESIGN

A TcPO2 sensor was fixed at the tarsometatarsal area of contralateral unwounded feet. A suction pressure of -125 mm Hg was applied until TcPO2 reached a steady state. The TcPO2 values for diabetic feet were measured before, during, and after NPWT.

MAIN RESULTS

The TcPO2 levels decreased significantly after applying NPWT in all patients. Mean TcPO2 values before, during, and after therapy were 44.6 (SD, 15.2), 6.0 (SD, 7.1), and 40.3 (SD, 16.4) mm Hg (P < .01), respectively.

CONCLUSION

These results show that NPWT significantly reduces tissue oxygenation levels in diabetic feet.

Assessment of Subtle Changes in Diabetes-Associated Arteriosclerosis using Photoplethysmographic Pulse Wave from Index Finger

Distortions in macro- and microcirculation are principal contributors to diabetes-associated complications. This study aimed at investigating the validity of applying non-invasive photoplethysmographic (PPG) waveform parameters in detecting diabetes-induced subtitle changes in arterial stiffness. Between July 2009 and October 2010, totally 94 middle-aged and elderly subjects were recruited including 48 without diabetes (Group 1) and 46 with the disease (Group 2). Demographic (i.e., age, gender), anthropometric (body-mass index), biochemical (i.e., glycated hemoglobin concentration), and hemodynamic (i.e., systolic blood pressure, heart rate) parameters were obtained. Crest time (CT) and crest time ratio (CTR) computed from PPG signals acquired from left index finger were compared with left index finger pulse wave velocity (PWV_finger) obtained from six-channel ECG-PWV system to investigate the differences between the two groups and the associations of these indices with the parameters of testing subjects. Significant difference was only noted in CTR between the two groups (P < 0.005). Despite correlation of both CT and CTR with age, only CTR demonstrated significant associations with hemodynamic parameters. CTR could differentiate diabetic patients from healthy individuals despite absence of difference in arterial stiffness assessed by conventional PWV, highlighting its superior sensitivity to subtle changes in diabetes-associated arteriosclerosis.

Post-occlusive reactive hyperaemia of skin microvasculature and foot complications in type 2 diabetes

AIMS

Diabetes-related microvascular disease has been implicated in the development of foot ulceration and amputation. Assessment of microvascular function may be effective in identifying those at risk of diabetic foot complications. We investigated the relationship between active or previous foot complication and post-occlusive reactive hyperaemia (PORH) measured by laser-Doppler fluxmetry (LDF) in people with type 2 diabetes.

METHODS

PORH measures were obtained from the hallux apex in 105 people with type 2 diabetes. Associations were investigated between active or previous foot complication and PORH measures: time to peak (TtPeak) and peak as a percentage of baseline (P%BL). Multinomial logistic regression was used to determine the association of PORH with the likelihood of active foot ulcer or previous foot complication.

RESULTS

For each second increase in TtPeak, the likelihood of a participant having a history of foot complication is increased by 2% (OR=1.019, p=0.01). This association was not reflected in people with an active foot ulcer (OR=1.003, p=0.832). P%BL was not found to be significantly different between those with a current or previous foot complication and those without (p=0.404).

CONCLUSIONS

This investigation in a cohort with type 2 diabetes has demonstrated that longer TtPeak is associated with history of diabetic foot complications.

Non-invasive lower limb small arterial measures co-segregate strongly with foot complications in people with diabetes

AIMS

It is unclear how well non-invasive lower-limb vascular assessments can identify those at risk of foot complications in people with diabetes. We aimed to investigate the relationship between a history of foot complication (ulceration or amputation) and non-invasive vascular assessments in people with diabetes.

METHODS

Bilateral ankle-brachial index (ABI), toe brachial index (TBI) and continuous wave Doppler (CWD) were performed in 127 adults with diabetes (97% type 2; age 66.08±11.4years; 55% men; diabetes duration 8.8±7.6years; 28% on insulin therapy; 31% with foot complication history. Correlations were performed between known risk factors for, and documented history of, foot complication. Regression analysis was used to determine the effect of TBI on the likelihood of a prior foot complication.

RESULTS

By logistic regression, the likelihood of foot complication history was highest in those with TBI <0.6 (OR=7.74, p=0.001); then longer diabetes duration (OR=1.06, p=0.05). HbA1c did not independently predict history of foot complications (OR=1.10, p=0.356).

CONCLUSIONS

Likelihood of previous foot complication in this population was ~8 times higher when TBI was <0.6. Such clinical risk profiling was not shown by other non-invasive measures. Prioritizing TBI as a measure of lower-limb vascular disease may be useful to prospectively identify those at risk of diabetic foot complications.

Foot bone density in diabetes may be unaffected by the presence of neuropathy

AIMS

Neuropathies are common complications of diabetes and are proposed to influence peripheral bone, principally via an altered vascular supply. This study aimed to determine the relationship between subtypes of neuropathy and vascular reactivity on foot bone density in people with diabetes.

METHODS

A case-control observational design was utilised with two groups: those with diabetic peripheral large fibre neuropathy (n=23) and a control group with diabetes but without neuropathy (n=23). Bone density in 12 foot bones was determined with computed tomography scanning. Additionally, post-occlusive reactive hyperemia, presence of small fibre neuropathy and heart rate variability were determined. T-tests and hierarchical regression were used to examine the relationships among the variables.

RESULTS

No difference in foot bone density was found between those with and those without large fibre neuropathy. Furthermore, no association between heart rate variability or reactive hyperemia and bone density was found. Small fibre neuropathy was associated with increased cuboid trabecular bone density (p=0.006) with its presence predictive of 14% of the variance.

CONCLUSIONS

This study found no clear association between presence of diabetic neuropathies and foot bone density. Furthermore, vascular reactivity appears to have no impact on bone density.

The effect of exercise training on cutaneous microvascular reactivity: A systematic review and meta-analysis

OBJECTIVES

This study aimed to review the efficacy of exercise training for improving cutaneous microvascular reactivity in response to local stimulus in human adults.

DESIGN

Systematic review with meta-analysis.

METHODS

A systematic search of Medline, Cinahl, AMED, Web of Science, Scopus, and Embase was conducted up to June 2015. Included studies were controlled trials assessing the effect of an exercise training intervention on cutaneous microvascular reactivity as instigated by local stimulus such as local heating, iontophoresis and post-occlusive reactive hyperaemia. Studies where the control was only measured at baseline or which included participants with vasospastic disorders were excluded. Two authors independently reviewed and selected relevant controlled trials and extracted data. Quality was assessed using the Downs and Black checklist.

RESULTS

Seven trials were included, with six showing a benefit of exercise training but only two reaching statistical significance with effect size ranging from -0.14 to 1.03. The meta-analysis revealed that aerobic exercise had a moderate statistically significant effect on improving cutaneous microvascular reactivity (effect size (ES)=0.43, 95% CI: 0.08-0.78, p=0.015).

CONCLUSIONS

Individual studies employing an exercise training intervention have tended to have small sample sizes and hence lacked sufficient power to detect clinically meaningful benefits to cutaneous microvascular reactivity. Pooled analysis revealed a clear benefit of exercise training on improving cutaneous microvascular reactivity in older and previously inactive adult cohorts. Exercise training may provide a cost-effective option for improving cutaneous microvascular reactivity in adults and may be of benefit to those with cardiovascular disease and metabolic disorders such as diabetes.

Can macrocirculation changes predict nonhealing diabetic foot ulcers?

PURPOSE

Transcutaneous partial oxygen tension (TcpO2) is considered the gold standard for assessment of tissue oxygenation, which is an essential factor for wound healing. The purpose of this study was to evaluate the association between macrocirculation and TcpO2 in persons with diabetes mellitus.

SUBJECTS AND SETTING

Ninety-eight patients with diabetic foot ulcers participated in the study (61 men and 37 women). The subjects had a mean age of 66.6 years (range, 30-83 years) and were treated at the Diabetic Wound Center of Korea University Guro Hospital, Seoul, Republic of Korea.

METHODS

Macrocirculation was evaluated using 2 techniques: computed tomographic angiography and Doppler ultrasound. Macrocirculation scores were based on the patency of the two tibial arteries in 98 patients. Computed tomographic angiography and Doppler ultrasound scores (0-4 points) were given according to intraluminal filling defects and arterial pulse waveform of each vessel, respectively. Tissue oxygenation was measured by TcpO2. Macrocirculation scores were statistically analyzed as a function of the TcpO2.

RESULTS

Statistical analysis revealed no significant linear trend between the macrocirculation status and TcpO2. Biavariate analysis using the Fisher exact test, Mantel-Haenszel tests, and McNemar-Bowker tests also found no significant relationship between macrocirculation and TcpO2.

CONCLUSIONS

Computed tomographic angiography and Doppler ultrasound are not sufficiently reliable substitutes for TcpO2 measurements in regard to determining the optimal treatment for diabetic patients.

Peripheral sensory neuropathy is associated with altered postocclusive reactive hyperemia in the diabetic foot

OBJECTIVE

This study examined whether the presence of peripheral sensory neuropathy or cardiac autonomic deficits is associated with postocclusive reactive hyperemia (reflective of microvascular function) in the diabetic foot.

RESEARCH DESIGN AND METHODS

99 participants with type 2 diabetes were recruited into this cross-sectional study. The presence of peripheral sensory neuropathy was determined with standard clinical tests and cardiac autonomic function was assessed with heart rate variation testing. Postocclusive reactive hyperemia was measured with laser Doppler in the hallux. Multiple hierarchical regression was performed to examine relationships between neuropathy and the peak perfusion following occlusion and the time to reach this peak.

RESULTS

Peripheral sensory neuropathy predicted 22% of the variance in time to peak following occlusion (p<0.05), being associated with a slower time to peak but was not associated with the magnitude of the peak. Heart rate variation was not associated with the postocclusive reactive hyperemia response.

CONCLUSIONS

This study found an association between the presence of peripheral sensory neuropathy in people with diabetes and altered microvascular reactivity in the lower limb.

Efficacy of low level laser therapy on painful diabetic peripheral neuropathy

BACKGROUND & AIMS

Diabetic peripheral neuropathy (DPN) accounts for most common complications of T2DM. Painful DPN is associated with functional limitation & poor quality of life. Therefore, objective of the study is to find the effect of low level laser therapy on painful diabetic peripheral neuropathy (DPN) in type 2 diabetes mellitus (T2DM) Materials & methods: The study design is pre-post observational design. After obtaining ethical clearance and informed consent, 19 T2DM subjects were screened and confirmed for peripheral neuropathy in an outpatient setting with biochemical parameter, pain scale and Michigan Neuropathy Screening Instrument (MNSI). Low Level Laser therapy was irradiated through scanning mode with dosage of 3.1J/cm(2) on the plantar and dorsum of the foot and 3.4j/cm(2) with contact method for 10days and all subjects were reassessed at the end of the 10 day. Descriptive statistics and paired' test was used to analyze the pre-post finding within the group. Level of significance was set at p<0.05 RESULTS: The result analysis showed significant reduction in Pain using VAS scale (6.47 ± 0.84 to 1.21 ± 0.78 (p<0.001), MNSI (5.52 ± 1.26 to 2.71 ± 0.97 (reduction in Vibration perception threshold (32.68 ± 6.08 to 24.84 ± 4.29 (<0.001) and a significant increase in the temperature from baseline to post intervention (30.01 ± 2.11 to 31.75 ± 1.03 (p<0. 001).

CONCLUSION

In the present study, Low level laser therapy was found to be effective in type 2 DM with peripheral neuropathy.

Automated Peripheral Neuropathy Assessment Using Optical Imaging and Foot Anthropometry

A large proportion of individuals who live with type-2 diabetes suffer from plantar sensory neuropathy. Regular testing and assessment for the condition is required to avoid ulceration or other damage to patient's feet. Currently accepted practice involves a trained clinician testing a patient's feet manually with a hand-held nylon monofilament probe. The procedure is time consuming, labor intensive, requires special training, is prone to error, and repeatability is difficult. With the vast increase in type-2 diabetes, the number of plantar sensory neuropathy sufferers has already grown to such an extent as to make a traditional manual test problematic. This paper presents the first investigation of a novel approach to automatically identify the pressure points on a given patient's foot for the examination of sensory neuropathy via optical image processing incorporating plantar anthropometry. The method automatically selects suitable test points on the plantar surface that correspond to those repeatedly chosen by a trained podiatrist. The proposed system automatically identifies the specific pressure points at different locations, namely the toe (hallux), metatarsal heads and heel (Calcaneum) areas. The approach is generic and has shown 100% reliability on the available database used. The database consists of Chinese, Asian, African, and Caucasian foot images.

Intratester and Intertester Reliability of Toe Pressure Measurements in People with and Without Diabetes Performed by Podiatric Physicians

BACKGROUND

Toe pressures and the toe brachial index (TBI) represent possible screening tools for peripheral arterial disease; however, limited evidence is available regarding their reliability. The aim of this study was to determine intratester and intertester reliability of toe systolic pressure and the TBI in participants with and without diabetes performed by podiatric physicians.

METHODS

Two podiatric physicians performed toe and brachial pressure measurements on 80 participants, 40 with and 40 without diabetes, during two testing sessions using photoplethysmography and Doppler probe. Intraclass correlation coefficients (ICCs) and 95% limits of agreement were determined.

RESULTS

In people with diabetes, intratester reliability of toe pressure measurement was excellent for both testers (ICCs, 0.84 and 0.82). Reliability of the TBI was good (ICCs, 0.72 and 0.75) and brachial pressure fair (ICCs, 0.43 and 0.55). The intertester reliability of toe pressure (ICC, 0.82) and the TBI (ICC, 0.80) was excellent. Intertester reliability of brachial pressure was reduced in people with diabetes (ICC, 0.49). In age-matched participants, intratester reliability of toe pressure measurement was excellent for both testers (ICCs, 0.83 and 0.87), and reliability of the TBI (ICCs, 0.74 and 0.80) and brachial pressure (ICCs, 0.73 and 0.78) was good to excellent. Intertester reliability of toe pressure (ICC, 0.84), the TBI (ICC, 0.81), and brachial pressure (ICC, 0.77) was excellent.

CONCLUSIONS

Toe pressures and the TBI demonstrated excellent reliability in people with and without diabetes and can be an effective component of lower-extremity vascular screening. However, wide limits of agreement relative to blood pressure values for both cohorts indicate that results should be interpreted with caution.

Differences in skin microcirculation on the upper and lower extremities in patients with diabetes mellitus: relationship of diabetic neuropathy and skin microcirculation

INTRODUCTION

During recent years, the role of microcirculation has received increasing attention especially for its potential pathogenic role in the development of diabetes complications, particularly diabetic foot syndrome. The aim of this study was to evaluate the differences in the skin microcirculatory reactivity on the upper and lower extremities (UE and LE, respectively) in the patient with type 2 diabetes mellitus (T2DM). We also evaluated the changes in the skin microcirculation independently of the individual test for peripheral diabetic neuropathy (DN) diagnosis (Semmes-Weinstein monofilaments, Bio-Thesiometer [Bio-Medical Instrument Co., Newbury, OH], and Neuropad(®) [TRIGOcare International GmbH, Wiehl, Germany]).

PATIENTS AND METHODS

Fifty-two patients with T2DM were enrolled. Microvascular reactivity was measured by laser Doppler iontophoresis, using 1% acetylcholine chloride (ACH) and 1% sodium nitroprusside.

RESULTS

Significant reduction of perfusion was found in LE compared with UE when using ACH. In patients with DN skin microvascular reactivity on LE and UE was reduced, compared with patients without DN. Impaired skin microvascular reactivity to ACH (dominant on LE) was demonstrated in all patients who were positive in at least one of the tests for the presence of DN.

CONCLUSIONS

Reactivity of the skin microcirculation is worse on the foot than on the hand. This study confirmed a close relationship of DN and impaired skin microcirculation. It seems that autonomous neuropathy (assessed using the Neuropad) precedes the manifestation of somatosensory neuropathy.

Repeatability of infrared plantar thermography in diabetes patients: a pilot study

OBJECTIVE

Infrared (IR) thermography has been used as a complementary diagnostic method in several pathologies, including distal diabetic neuropathy, by tests that induce thermoregulatory responses, but nothing is known about the repeatability of these tests. This study aimed to assess the repeatability of the rewarming index in subjects with type 2 diabetes mellitus (T2DM) and nondiabetic control subjects.

METHODS

Using an IR camera, plantar IR images were collected at baseline (pre-) and 10 min after (post-) cold stress testing on two different days with 7 days interval. Plantar absolute average temperatures pre- and post-cold stress testing, the difference between them (ΔT), and the rewarming index were obtained and compared between days. Repeatability of the rewarming index after the cold stress test was assessed by Bland-Altman plot limits of agreement.

RESULTS

Ten T2DM subjects and ten nondiabetic subjects had both feet analyzed. Mean age did not differ between groups (p = .080). Absolute average temperatures of plantar region pre- (p = .033) and post-cold stress test (p = .019) differed between days in nondiabetic subjects, whereas they did not differ in T2DM subjects (pretest, p = .329; post-test, p = .540). ΔT and rewarming index did not differ between days for both groups, and the rewarming index presented a 100% agreement of day-to-day measurements from T2DM subjects and 95% with nondiabetic subjects.

CONCLUSIONS

The rewarming index after cold stress testing presented good repeatability between two days a week in both groups. Despite T2DM subjects presenting no differences on absolute temperature values between days, ΔT or rewarming index after cold stress testing remain recommended beside absolute temperature values for clinical use.

COX-2-derived prostanoids and oxidative stress additionally reduce endothelium-mediated relaxation in old type 2 diabetic rats

Endothelial dysfunction in resistance arteries alters end organ perfusion in type 2 diabetes. Superoxides and cyclooxygenase-2 (COX-2) derivatives have been shown separately to alter endothelium-mediated relaxation in aging and diabetes but their role in the alteration of vascular tone in old diabetic subjects is not clear, especially in resistance arteries. Consequently, we investigated the role of superoxide and COX-2-derivatives on endothelium-dependent relaxation in 3 and 12 month-old Zucker diabetic fatty (ZDF) and lean (LZ) rats. Mesenteric resistance arteries were isolated and vascular tone was investigated using wire-myography. Endothelium (acetylcholine)-dependent relaxation was lower in ZDF than in LZ rats (60 versus 84% maximal relaxation in young rats and 41 versus 69% in old rats). Blocking NO production with L-NAME was less efficient in old than in young rats. L-NAME had no effect in old ZDF rats although eNOS expression level in old ZDF rats was similar to that in old LZ rats. Superoxide level and NADPH-oxidase subunits (p67phox and gp91phox) expression level were greater in ZDF than in LZ rats and were further increased by aging in ZDF rats. In young ZDF rats reducing superoxide level with tempol restored acetylcholine-dependent relaxation to the level of LZ rats. In old ZDF rats tempol improved acetylcholine-dependent relaxation without increasing it to the level of LZ rats. COX-2 (immunolabelling and Western-blot) was present in arteries of ZDF rats and absent in LZ rats. In old ZDF rats arterial COX-2 level was higher than in young ZDF rats. COX-2 blockade with NS398 restored in part acetylcholine-dependent relaxation in arteries of old ZDF rats and the combination of tempol and NS398 fully restored relaxation in control (LZ rats) level. Accordingly, superoxide production and COX-2 derivatives together reduced endothelium-dependent relaxation in old ZDF rats whereas superoxides alone attenuated relaxation in young ZDF or old LZ rats.

Increased stability of S-nitrosothiol solutions via pH modulations

S-nitrosothiol (RSNO) solutions represent a valuable source of nitric oxide and could be used as topical vasodilators, but their fast decomposition rate poses a serious obstacle to their potentially widespread therapeutic use. Our aim was to characterize and quantify the effect of pH on S-nitrosothiol formation and decomposition in simple aqueous solutions of S-nitrosoglutathione (GSNO), S-nitroso-N-acetylcysteine (SNAC) and S-nitroso-3-mercaptopropionic acid (SN3MPA). Furthermore, we investigated the effect of storage pH on the stability of GSNO incorporated in poly(ethylene glycol)/ poly(vinyl alcohol) matrices. S-nitrosothiol concentrations were measured spectrophotometrically and laser Doppler scanning method was used to assess dermal blood flow. GSH and NAC solutions reached a complete transformation to nitrosothiols when synthesized using acidic NaNO(2) solution. The initial concentration of all investigated RSNOs decreased more slowly with pH adjusted to mildly basic values (8.4-8.8) for the storage period. Polymer gels of PVA/PEG compositions at mildly basic storage pH further reduced the decomposition rate succeeding to contain 46.8% of the initial GSNO concentration for 25 days. This amount of topically administered GSNO was still capable of increasing the dermal blood flow over 200% in human subjects.

Inhibiting TRPA1 ion channel reduces loss of cutaneous nerve fiber function in diabetic animals: sustained activation of the TRPA1 channel contributes to the pathogenesis of peripheral diabetic neuropathy

Peripheral diabetic neuropathy (PDN) is a devastating complication of diabetes mellitus (DM). Here we test the hypothesis that the transient receptor potential ankyrin 1 (TRPA1) ion channel on primary afferent nerve fibers is involved in the pathogenesis of PDN, due to sustained activation by reactive compounds generated in DM. DM was induced by streptozotocin in rats that were treated daily for 28 days with a TRPA1 channel antagonist (Chembridge-5861528) or vehicle. Laser Doppler flow method was used for assessing axon reflex induced by intraplantar injection of a TRPA1 channel agonist (cinnamaldehyde) and immunohistochemistry to assess substance P-like innervation of the skin. In vitro calcium imaging and patch clamp were used to assess whether endogenous TRPA1 agonists (4-hydroxynonenal and methylglyoxal) generated in DM induce sustained activation of the TRPA1 channel. Axon reflex induced by a TRPA1 channel agonist in the plantar skin was suppressed and the number of substance P-like immunoreactive nerve fibers was decreased 4 weeks after induction of DM. Prolonged treatment with Chembridge-5861528 reduced the DM-induced attenuation of the cutaneous axon reflex and loss of substance P-like immunoreactive nerve fibers. Moreover, in vitro calcium imaging and patch clamp results indicated that reactive compounds generated in DM (4-hydroxynonenal and methylglyoxal) produced sustained activations of the TRPA1 channel, a prerequisite for adverse long-term effects. The results indicate that the TRPA1 channel exerts an important role in the pathogenesis of PDN. Blocking the TRPA1 channel provides a selective disease-modifying treatment of PDN.

Correlation between plantar foot temperature and diabetic neuropathy: a case study by using an infrared thermal imaging technique

BACKGROUND

Diabetic neuropathy consists of multiple clinical manifestations of which loss of sensation is most prominent. High temperatures under the foot coupled with reduced or complete loss of sensation can predispose the patient to foot ulceration. The aim of this study was to look at the correlation between plantar foot temperature and diabetic neuropathy using a noninvasive infrared thermal imaging technique.

METHODS

Infrared thermal imaging, a remote and noncontact experimental tool, was used to study the plantar foot temperatures of 112 subjects with type 2 diabetes selected from a tertiary diabetes centre in South India.

RESULTS

Patients with diabetic neuropathy (defined as vibration perception threshold (VPT) values on biothesiometry greater than 20 V) had a higher foot temperature (32-35 °C) compared to patients without neuropathy (27-30 °C). Diabetic subjects with neuropathy also had higher mean foot temperature (MFT) (p=.001) compared to non-neuropathic subjects. MFT also showed a positive correlation with right great toe (r=0.301, p=.001) and left great toe VPT values (r=0.292, p=.002). However, there was no correlation between glycated hemoglobin and MFT.

CONCLUSIONS

Infrared thermal imaging may be used as an additional tool for evaluation of high risk diabetic feet.

Is the foot elevation the optimal position for wound healing of a diabetic foot?

In managing diabetic foot ulcers, foot elevation has generally been recommended to reduce oedema and prevent other sequential problems. However, foot elevation may decrease tissue oxygenation of the foot more than the dependent position since the dependent position is known to increase blood flow within the arterial system. In addition, diabetic foot ulcers, which have peripheral vascular insufficiency, generally have less oedema than other wounds. Therefore, we argue that foot elevation may not be helpful for healing of vascularly compromised diabetic foot ulcers since adequate tissue oxygenation is an essential factor in diabetic wound healing. The purpose of this study was to evaluate the influence of foot height on tissue oxygenation and to determine the optimal foot position to accelerate wound healing of diabetic foot ulcers. This study included 122 cases (73 males and 47 females; two males had bilateral disease) of diabetic foot ulcer patients aged 40-93 years. Trans-cutaneous partial oxygen tension (TcpO(2)) values of diabetic feet were measured before and after foot elevation (n=21). Elevation was achieved by placing a foot over four cushions. We also measured foot TcpO(2) values before and after lowering the feet (n=122). Feet were lowered to the patient's tibial height, approximately 30-35 cm, beside a bed handrail. Due to the large number of lowering measurements, we divided them into five sub-groups according to initial TcpO(2.) Tissue oxygenation values were compared. Foot-elevation-lowered TcpO(2) values before and after elevation were 32.5+/-22.2 and 23.8+/-23.1 mmHg (p<0.01), respectively. Foot-lowering-augmented TcpO(2) values before and after lowering were 44.6+/-23.8 and 58.0+/-25.9 mmHg (p<0.01), respectively. The lower the initial TcpO(2) level, the more the TcpO(2) level increased. The foot lowering, rather than elevation, significantly augments TcpO(2) and may stimulate healing of diabetic foot ulcers.

Association between asymptomatic median mononeuropathy and diabetic polyneuropathy severity in patients with diabetes mellitus

BACKGROUND

Asymptomatic median mononeuropathy (AMM) and diabetic polyneuropathy (DPN) often coexist and can be difficult to distinguish electrophysiologically. Moreover, the potential association between AMM and DPN has not been extensively evaluated.

OBJECTIVE

We investigated the relation between AMM and DPN severity in consecutive diabetic patients.

METHODS

The non-dominant limb was studied electrophysiologically in 100 consecutive diabetic patients with no symptoms of carpal tunnel syndrome on the non-dominant side. AMM was diagnosed based on previously validated electrophysiological criteria. DPN severity was graded according to the Michigan diabetic neuropathy score.

RESULTS

AMM was discovered in 28% of the study population (Adjusted Wald 95% CI: 20%-37%). It was more common in women, displayed a tendency of being more common in patients over 50 years old and correlated with the severity of DPN and the number of abnormal nerves on nerve conduction studies. It was present in 18.1% of patients without evidence of DPN. No correlation was found with the duration and type of diabetes. In multivariate logistic regression models increasing severity of DPN was independently associated with the presence AMM (Wald test=10.557, df=3, p=0.014). Patients with DPN stage III and IV had a five-fold (OR=5.06, 95% CI=1.49-17.19) and a four-fold (OR=4.50, 95% CI=1.15-17.65) respectively increased likelihood to present with AMM in comparison to DPN stage I (reference group).

CONCLUSIONS

Our results confirmed the high incidence of AMM in diabetic patients. AMM was present in a significant number of patients in the absence of DPN and the likelihood of AMM detection increased with increasing severity of DPN.

The effect of alpha-lipoic acid on symptoms and skin blood flow in diabetic neuropathy

AIMS

Multiple pathogenic pathways are involved in diabetic neuropathy and diverse treatments have been tried without success. The aim of this study was to assess the effect of alpha-lipoic acid on skin blood flow in patients with diabetic neuropathy.

METHODS

We measured skin blood flow in 13 control subjects and 19 patients with diabetic neuropathy using the laser Doppler blood flow technique. Skin blood flow and the extent of skin blood flow changes were compared before and after diabetic patients received 600 mg/day alpha-lipoic acid intravenously for 14 days.

RESULTS

Although no significant differences in absolute values of skin blood flow or in the extent of changes were noted, symptoms were reduced after alpha-lipoic acid treatment.

CONCLUSIONS

This study suggests that alpha-lipoic acid, a potent antioxidant, improves symptoms of diabetic neuropathy. Larger studies are needed to determine whether improvements in skin blood flow also occur in patients with diabetic neuropathy.