Impaired distal thermoregulation in diabetes and diabetic polyneuropathy

Sleeping for One Week on a Temperature-Controlled Mattress Cover Improves Sleep and Cardiovascular Recovery

Body temperature should be tightly regulated for optimal sleep. However, various extrinsic and intrinsic factors can alter body temperature during sleep. In a free-living study, we examined how sleep and cardiovascular health metrics were affected by sleeping for one week with (Pod ON) vs. without (Pod OFF), an active temperature-controlled mattress cover (the Eight Sleep Pod). A total of 54 subjects wore a home sleep test device (HST) for eight nights: four nights each with Pod ON and OFF (>300 total HST nights). Nightly sleeping heart rate (HR) and heart rate variability (HRV) were collected. Compared to Pod OFF, men and women sleeping at cooler temperatures in the first half of the night significantly improved deep (+14 min; +22% mean change; p = 0.003) and REM (+9 min; +25% mean change; p = 0.033) sleep, respectively. Men sleeping at warm temperatures in the second half of the night significantly improved light sleep (+23 min; +19% mean change; p = 0.023). Overall, sleeping HR (-2% mean change) and HRV (+7% mean change) significantly improved with Pod ON (p < 0.01). To our knowledge, this is the first study to show a continuously temperature-regulated bed surface can (1) significantly modify time spent in specific sleep stages in certain parts of the night, and (2) enhance cardiovascular recovery during sleep.

Diurnal rhythms of wrist temperature are associated with future disease risk in the UK Biobank

Many chronic disease symptomatologies involve desynchronized sleep-wake cycles, indicative of disrupted biorhythms. This can be interrogated using body temperature rhythms, which have circadian as well as sleep-wake behavior/environmental evoked components. Here, we investigated the association of wrist temperature amplitudes with a future onset of disease in the UK Biobank one year after actigraphy. Among 425 disease conditions (range n = 200-6728) compared to controls (range n = 62,107-91,134), a total of 73 (17%) disease phenotypes were significantly associated with decreased amplitudes of wrist temperature (Benjamini-Hochberg FDR q < 0.05) and 26 (6.1%) PheCODEs passed a more stringent significance level (Bonferroni-correction α < 0.05). A two-standard deviation (1.8° Celsius) lower wrist temperature amplitude corresponded to hazard ratios of 1.91 (1.58-2.31 95% CI) for NAFLD, 1.69 (1.53-1.88) for type 2 diabetes, 1.25 (1.14-1.37) for renal failure, 1.23 (1.17-1.3) for hypertension, and 1.22 (1.11-1.33) for pneumonia (phenome-wide atlas available at http://bioinf.itmat.upenn.edu/biorhythm_atlas/ ). This work suggests peripheral thermoregulation as a digital biomarker.

Diurnal rhythmicity of wearable device-measured wrist temperature predicts future disease incidence in the UK Biobank

Many chronic disease symptomatologies involve desynchronized sleep-wake cycles, indicative of disrupted biorhythms. This can be interrogated using body temperature rhythms, which are well-established biomarkers for circadian clock function. Here, we investigated the association of wrist temperature amplitudes with a future onset of disease in the UK Biobank one year after actigraphy. Among 425 disease conditions (range n =  200-6,728) compared to controls (range n =  62,107 - 91,134), a total of 73 (36.5%) disease phenotypes were significantly associated with decreased amplitudes of wrist temperature (Benjamini-Hochberg FDR q < 0.05) and 26 (13%) PheCODEs passed a more stringent significance level (Bonferroni-correction α < 0.05). Here, for example, a two-standard deviation (1.8° Celsius) lower wrist temperature amplitude corresponded to hazard ratios of 1.91 (1.58-2.31 95% CI) for NAFLD, 1.69 (1.53-1.88) for type 2 diabetes, 1.25 (1.14-1.37) for renal failure, 1.23 (1.17-1.3) for hypertension, and 1.22 (1.11-1.33) for pneumonia. A comprehensive phenome-wide atlas of the identified mappings has been made available at http://bioinf.itmat.upenn.edu/biorhythm_atlas/. These findings strongly suggest peripheral thermoregulation as a digital biomarker.

Urban-rural disparity in heatwave effects on diabetes mortality in eastern China: A case-crossover analysis in 2016-2019

Diabetics are sensitive to high ambient temperature due to impaired thermoregulation. However, available evidence on the impact of prolonged high temperature (i.e., heatwave) on diabetes deaths is limited and whether urban and rural areas differ in heatwave vulnerability remains unknown so far. A time-stratified case-crossover analysis was employed to estimate the association between heatwaves and diabetes deaths in 1486 districts (509 urban and 977 rural areas) of eastern China (Jiangsu Province), 2016-2019. For each decedent, residential heatwave exposure was measured by matching daily mean temperatures to the geocoded residential address. We adopted nine-tiered heatwave definitions incorporating intensity and duration. Stratified analyses by decedents' characteristics (gender, age, and education) were also conducted. During the study period, there were 18,685 deaths from diabetes (urban proportion: 36.95 %, p-value for urban-rural difference < 0.05). Heatwaves were associated with an increased risk of diabetes deaths, with greater and longer-lasting effects in rural areas than urban areas [e.g., rural odds ratio (OR): 1.19 (95 % confidence interval (CI): 1.14, 1.25) vs. urban OR: 1.09 (95 % CI: 1.05, 1.12)]. Risk of diabetes deaths increased with the intensity of heatwaves in rural areas (p-value for trend <0.01), but not in urban areas. Stratified analyses in rural areas suggested that females and less-educated people were more vulnerable to heatwave-related diabetes deaths. Our findings revealed the urban-rural disparity in the risk of diabetes deaths associated with heatwaves. Rural diabetics should be made aware of the increased death risk posed by heatwaves in the context of warming climate.

Functional links between thermoregulation and sleep in children with neurodevelopmental and chronic health conditions

The bi-directional relationship between sleep and wake is recognized as important for all children. It is particularly consequential for children who have neurodevelopmental disorders (NDDs) or health conditions which challenge their sleep and biological rhythms, and their ability to maintain rhythms of participation in everyday activities. There are many studies which report the diverse reasons for disruption to sleep in these populations. Predominantly, there is focus on respiratory, pharmaceutical, and behavioral approaches to management. There is, however, little exploration and explanation of the important effects of body thermoregulation on children's sleep-wake patterns, and associated behaviors. Circadian patterns of sleep-wake are dependent on patterns of body temperature change, large enough to induce sleep preparedness but remaining within a range to avoid sleep disturbances when active thermoregulatory responses against heat or cold are elicited (to maintain thermoneutrality). Additionally, the subjective notion of thermal comfort (which coincides with the objective concept of thermoneutrality) is of interest as part of general comfort and associated behavioral responses for sleep onset and maintenance. Children's thermoregulation and thermal comfort are affected by diverse biological functions, as well as their participation in everyday activities, within their everyday environments. Hence, the aforementioned populations are additionally vulnerable to disruption of their thermoregulatory system and their capacity for balance of sleep and wakefulness. The purpose of this paper is to present hitherto overlooked information, for consideration by researchers and clinicians toward determining assessment and intervention approaches to support children's thermoregulation functions and promote their subjective thermal comfort, for improved regulation of their sleep and wake functions.

Is There an Association between Sleep Disorders and Diabetic Foot? A Scoping Review

Diabetic foot is associated with a low quality of life since physical disabilities, mood disturbances and psychological disorders are frequent. One of the most important biological processes to ensure quality of life is sleep. Sleep disorders can impair glycemic control in patients with diabetes mellitus or even cause long-term type 2 diabetes mellitus. The aim of this study is to carry out a scoping review about the association between sleep cycle disorders and diabetic foot. PubMed, Scopus, CINAHL, PEDro, Cochrane Library, SCIELO and EMBASE databases were chosen for the search and the following terms were used: "diabetic foot","sleep*","rest-activity","mood" and"behavior". All the studies should include outcome variables about sleep and diabetic foot. Finally, 12 articles were selected, all of whichwere observational. The most frequent variables were those regarding diabetic foot ulcer aspects and diabetic neuropathy on one side, and obstructive sleep apnea, sleep duration and sleep quality on the other side. The results suggest that there is a possible association between obstructive sleep apnea and the presence or history of diabetic foot ulcers. No direct associations between sleep quality or sleep duration and diabetic foot or diabetic foot ulcer variables have been found.

Circadian Patterns of Patients with Type 2 Diabetes and Obstructive Sleep Apnea

Sleep apnea, a condition that modifies sleep and circadian rhythms, is highly prevalent in patients with diabetes. However, it is not known if there is an association between sleep apnea, circadian alterations and glycemic regulation in this type of patient. Here, a polysomnographic study was carried out on 21 women and 25 men (mean age = 64.3 ± 1.46 years) with diagnoses of type 2 diabetes to detect the presence of sleep apnea. Moreover, patients wore an actigraph and a temperature sensor on the wrist for one week, to study the manifestation of the circadian rhythms. The correlations of circadian and polysomnographic variables with the severity of apnea, measured by the apnea-hypopnea index, and with glycemic dysregulation, measured by the percentage of glycated hemoglobin, were analyzed. The mean apnea-hypoapnea index of all the participants was 39.6 ± 4.3. Apnea-hypoapnea index correlated with % N1, negatively with % N3, and also the stability of the active circadian rhythm. However, no significant correlation was found between the apnea-hypopnea index and wrist temperature rhythm and glycated hemoglobin. Glycated hemoglobin levels were negatively associated with the percentage of variance explained by the wrist temperature circadian rhythm (calculated via 24 and 12 h rhythms). This association was independent of body mass index and was strongest in patients with severe apnea. In conclusion, patients with diabetes showed altered circadian rhythms associated with a poor glycemic control and this association could partially be related to the coexistence of sleep apnea.

Selective Thermal Stimulation Delays the Progression of Vasoconstriction During Body Cooling

The objective of this study was to test the feasibility of Selective Thermal Stimulation (STS) as a method to upregulate glabrous skin blood flow. STS is accomplished by mild surface heating along the spinal cord. 4 healthy subjects were tested in this study. Each participated in a control experiment and an intervention experiment (STS). Both experiments included establishing a maximum level of vasodilation, considered unique to a subject on a test day, and then cooling to a maximum level of vasoconstriction. Perfusion was measured by a laser Doppler flow probe on the index fingertip. The percent of perfusion in the range of minimum to maximum was the primary outcome variable. The data was fit to a linear mixed effects model to determine if STS had a significant influence on perfusion during whole body cooling. STS had a statistically significant effect on perfusion and increased glabrous skin blood flow by 16.3% (P<.001, CI [13.1%, 19.5%]) as skin temperature was decreased. This study supports the theory that STS improves the heat exchanger efficiency of palmar and plantar surfaces by increasing the blood flow.

Battery-free, wireless sensors for full-body pressure and temperature mapping

Thin, soft, skin-like sensors capable of precise, continuous measurements of physiological health have broad potential relevance to clinical health care. Use of sensors distributed over a wide area for full-body, spatiotemporal mapping of physiological processes would be a considerable advance for this field. We introduce materials, device designs, wireless power delivery and communication strategies, and overall system architectures for skin-like, battery-free sensors of temperature and pressure that can be used across the entire body. Combined experimental and theoretical investigations of the sensor operation and the modes for wireless addressing define the key features of these systems. Studies with human subjects in clinical sleep laboratories and in adjustable hospital beds demonstrate functionality of the sensors, with potential implications for monitoring of circadian cycles and mitigating risks for pressure-induced skin ulcers.

The thermoregulation of healthy individuals, overweight-obese, and diabetic from the plantar skin thermogram: a clue to predict the diabetic foot

Background: Thermoregulation is a complex autonomic process to keep or to dissipate heat in the human body.

Methods: In this work, by means of the thermogram of the plantar skin, the thermoregulation of healthy individuals, overweight–obese, and diabetic is discussed.

Results: The thermograms of the plantar skin, for the healthy individuals, are: (1) symmetrical, the temperature distribution of the right foot being a mirror image of that of the left foot ; (2) the thermograms of women, on average, are 3°C colder than those of the men; and (3) the temperature distributions decrease distally from the medial longitudinal arch. The plantar skin thermograms of overweight–obese individuals show: (1) increased average temperature of both feet and for both genders; (2) no symmetry between the left and right feet thermograms; and (3) the temperature distribution is still decreasing from the medial longitudinal arch to the periphery of the foot. However, the standard deviation, for each averaged temperature of the angiosomes, shows greater uncertainty. Most thermograms of diabetic individuals show temperature increase on the plantar skin, and are mostly symmetric between left and right feet.

Conclusions: An asymmetric thermogram of the plantar skin of diabetic individuals, where one foot is hotter than the other, may mean that the coldest foot is losing the capacity to communicate properly with the central nervous system and/or that vasoconstriction/vasodilatation is having problems in regulating the passing of blood through the vessels. Thus, the asymmetric thermograms of diabetic patients, and particularly those coldest regions of foot are of interest, because of the reduction of the local autonomic sensing and the lack of achieving properly the passing of the blood.

Disrupted circadian rhythms of body temperature, heart rate and fasting blood glucose in prediabetes and type 2 diabetes mellitus

We report a progressive disruption of 24-h rhythms in fasting blood glucose (FBG), body temperature (BT) and heart rate (HR) associated with metabolic dysfunction and the development of prediabetes (PD) and type 2 diabetes mellitus (T2DM) in overweight middle-aged (40-69 years old) humans. Increasing BT and HR mean values and declining 24-h BT and HR amplitudes accompany adverse changes in metabolic state. Increased nocturnal BT and a phase delay of the 24-h BT rhythm, deviant 24-h HR profile and a phase advance of the 24-h HR and FBG rhythms are early signs of the PD metabolic state. In T2DM, the 24-h FBG rhythm is no longer detectable, and the 24-h amplitudes of BT and HR are greatly diminished. In addition, lepton and creatinine values were lowered in T2DM. Moreover, positive correlations between FBG and body mass index, BMI, and negative correlations between the 24-h amplitude of FBG and BMI indicate that overweight is an additional factor causing disruption of the circadian rhythms. Further studies on circadian disruption as a consequence of metabolic dysfunction are necessary. The quantitative analysis of changing circadian BT and HR rhythms may provide prognostic markers of T2DM and therapeutic targets for its prevention and correction.

Expected accuracy of proximal and distal temperature estimated by wireless sensors, in relation to their number and position on the skin

A popular method to estimate proximal/distal temperature (T_PROX and T_DIST) consists in calculating a weighted average of nine wireless sensors placed on pre-defined skin locations. Specifically, T_PROX is derived from five sensors placed on the infra-clavicular and mid-thigh area (left and right) and abdomen, and T_DIST from four sensors located on the hands and feet. In clinical practice, the loss/removal of one or more sensors is a common occurrence, but limited information is available on how this affects the accuracy of temperature estimates. The aim of this study was to determine the accuracy of temperature estimates in relation to number/position of sensors removed. Thirteen healthy subjects wore all nine sensors for 24 hours and reference T_PROX and T_DIST time-courses were calculated using all sensors. Then, all possible combinations of reduced subsets of sensors were simulated and suitable weights for each sensor calculated. The accuracy of T_PROX and T_DIST estimates resulting from the reduced subsets of sensors, compared to reference values, was assessed by the mean squared error, the mean absolute error (MAE), the cross-validation error and the 25^th and 75^th percentiles of the reconstruction error. Tables of the accuracy and sensor weights for all possible combinations of sensors are provided. For instance, in relation to T_PROX, a subset of three sensors placed in any combination of three non-homologous areas (abdominal, right or left infra-clavicular, right or left mid-thigh) produced an error of 0.13°C MAE, while the loss/removal of the abdominal sensor resulted in an error of 0.25°C MAE, with the greater impact on the quality of the reconstruction. This information may help researchers/clinicians: i) evaluate the expected goodness of their T_PROX and T_DIST estimates based on the number of available sensors; ii) select the most appropriate subset of sensors, depending on goals and operational constraints.

Walking cadence affects rate of plantar foot temperature change but not final temperature in younger and older adults

This study examined the relationship between (1) foot temperature in healthy individuals and walking cadence, (2) temperature change at different locations of the foot, and (3) temperature change and its relationship with vertical pressures exerted on the foot. Eighteen healthy adult volunteers (10 between 30 and 40 years - Age: 33.4±2.4years; 8 above 40 years - Age: 54.1±7.7years) were recruited. A custom-made insole with temperature sensors was placed directly onto the plantar surface of the foot and held in position using a sock. The foot was placed on a pressure sensor and the whole system placed in a canvas shoe. Participants visited the lab on three separate occasions when foot temperature and pressure data were recorded during walking on a treadmill at one of three cadences (80, 100, 120steps/min). The plantar foot temperature increased during walking in both age groups 30-40 years: 4.62±2.00°C, >40years: 5.49±2.30°C, with the rise inversely proportional to initial foot temperature (30-40 years: R²=-0.669, >40years: R²=-0.816). Foot temperature changes were not different between the two age groups or the different foot locations and did not depend on vertical pressures. Walking cadence affected the rate of change of plantar foot temperature but not the final measured value and no association between temperature change and vertical pressure was found. These results provide baseline values for comparing foot temperature changes in pathological conditions which could inform understanding of pathophysiology and support development of evidence based healthcare guidelines for managing conditions such as diabetic foot ulceration (DFU).

Congenital central hypoventilation syndrome (CCHS): Circadian temperature variation

BACKGROUND

Congenital central hypoventilation syndrome (CCHS) is a rare neurocristopathy, which includes a control of breathing deficit and features of autonomic nervous system (ANS) dysregulation. In recognition of the fundamental role of the ANS in temperature regulation and rhythm and the lack of any prior characterization of circadian temperature rhythms in CCHS, we sought to explore peripheral and core temperatures and circadian patterning. We hypothesized that CCHS patients would exhibit lower peripheral skin temperatures (PST), variability, and circadian rhythmicity (vs. controls), as well as a disrupted relationship between core body temperature (CBT) and PST.

METHODS

PST was sampled every 3 min over four 24-hr periods in CCHS cases and similarly aged controls. CBT was sampled in a subset of these recordings.

RESULTS

PST was recorded from 25 CCHS cases (110,664 measures/230 days) and 39 controls (78,772 measures/164 days). Simultaneous CBT measurements were made from 23 CCHS patients. In CCHS, mean PST was lower overall (P = 0.03) and at night (P = 0.02), and PST variability (interquartile range) was higher at night (P = 0.05) (vs. controls). PST circadian rhythm remained intact but the phase relationship of PST to CBT rhythm was extremely variable in CCHS.

CONCLUSIONS

PST alterations in CCHS likely reflect altered autonomic control of peripheral vascular tone. These alterations represent a previously unreported manifestation of CCHS and may provide an opportunity for therapeutic intervention. The relationship between temperature dysregulation and CCHS may also offer insight into basic mechanisms underlying thermoregulation.

Various patterns of disrupted daily rest-activity rhythmicity associated with diabetes

Disruptions to sleep and circadian rhythms have now been recognized as common comorbidities in patients with medical illnesses. We aimed to determine if the diurnal rhythms for rest and activity were disrupted in parallel with the development of diabetic complications. Ninety outpatients in our diabetes clinic who had a body mass index <25 kg m(2) wore an actigraph for 7 consecutive days (42 men; mean age 68.7 ± 8.2 years). Patients with neuropsychiatric diseases, liver cirrhosis, renal failure, chronic obstructive pulmonary disease or blindness, or those who performed shiftwork were excluded. We grouped the actigraph recordings into 1-h periods and counted the number of minutes that showed activity. Stepwise regression analysis showed an association between a diabetic clinical background and measurements of circadian rhythms such as daytime activity, night-time activity, phase, interdaily stability, intradaily variability and relative amplitude. Higher age, body mass index, total cholesterol levels and insulin usage were associated with lower daytime activity and higher intradaily variability, whereas higher haemoglobin A1c levels and the presence of neuropathy were associated with greater daytime activity. The presence of proliferative retinopathy and increased levels of microalbuminuria were associated with higher intradaily variability and lower interdaily stability and amplitude. The presence of cardiovascular disease was associated with advanced phase, whereas painful neuropathy was associated with delayed phase. Our study demonstrated that different diabetic complications were associated independently with a variety of alterations in the circadian rest and activity rhythms. Our findings have provided novel insights that may be helpful in developing interventions for sleep-wake disorders associated with diabetes.

A review of thermal methods and technologies for diabetic foot assessment

Temperature analysis has been considered as a complementary method in medical evaluation and diagnosis. Several studies demonstrated that monitoring the temperature variations of the feet of diabetic patients can be helpful in the early identification of diabetic foot manifestations, and also in changing behaviors, which may contribute to reducing its incidence. In this review, several and most used techniques for assessing the temperature of the feet are presented, along with original published work on specific applications in diabetic foot complications. A review of solutions and equipment that operate according to the temperature assessment techniques is also presented. Finally, a comparison between the various technologies is presented, and the authors share their perspective on what will be the state of affairs in 5 years.

New Molecular Techniques to Study the Skin Microbiota of Diabetic Foot Ulcers

Significance: Diabetic foot ulcers (DFU) are a major and growing public health problem. They pose difficulties in clinical practice in both diagnosis and management. Bacterial interactions on the skin surface are important in the pathophysiology of DFU and may contribute to a delay in healing. Fully identifying bacteria present in these wounds is difficult with traditional culture methods. New molecular tools, however, have greatly contributed to our understanding of the role of the cutaneous microbiota in DFU. Recent Advances: Molecular technologies revealed new information concerning how bacteria are organized in DFU. This has led to the concept of "functionally equivalent pathogroups," meaning that certain bacterial species which are usually nonpathogenic (or at least incapable of maintaining a chronic infection on their own) may coaggregate symbiotically in a pathogenic biofilm and act synergistically to cause a chronic infection. The distribution of pathogens in multispecies biofilms is nonrandom. The high bacterial diversity is probably related to the development of a microbial biofilm that is irreversibly attached to the wound matrix. Critical Issues: Using molecular techniques requires a financial outlay for high-cost equipment. They are still too time-consuming to perform and reporting is too delayed for them to be used in routine practice. Finally, they do not differentiate live from dead or pathogenic from nonpathogenic microorganisms. Future Directions: Molecular tools have better documented the composition and organization of the skin flora. Further advances are required to elucidate which among the many bacteria in the DFU flora are likely to be pathogens, rather than colonizers.

Impact of diabetes mellitus duration on effect of lower extremity nerve decompression in 1,526 diabetic peripheral neuropathy patients

BACKGROUND

Diabetic peripheral neuropathy (DPN) is one of the most common complications of diabetes mellitus (DM). The aim of this study was to analyze DM duration in the prognosis of diabetic peripheral neuropathy of the lower extremity.

METHODS

A total of 1,526 DPN patients who were treated with DELLON surgical nerve decompression were divided into a short DM duration group and long DM duration group using a length of 5 years as the standard duration. Before and 1.5 years after surgery, high-resolution ultrasound, quantitative sensory testing (QST), and nerve conduction velocity (NCV) were performed and compared to the normal control.

RESULTS

Postoperative NCV of all the patients in either treatment group significantly increased (p < 0.05) and postoperative CSA significantly decreased (p < 0.05) compared with that before surgery. The CPT significantly increased compared with the preoperative value (p < 0.05). The postoperative WPT was significantly lower than the preoperative value (p < 0.01), and the postoperative VPT was significantly lower than the preoperative value (p < 0.05). Overall, the postoperative NCV, CSA, CPT, WPT, and VPT values from the short DM duration group were significantly different from that of the long DM duration group (p < 0.05).

CONCLUSIONS

The duration of DM is critical to the prognosis of DPN of the lower extremity, and the data from this study suggest that an early diagnosis and subsequent surgery for DPN have important clinical value.

Assessment of endothelial dysfunction in patients with impaired glucose tolerance during a cold pressor test

The objective of this study is to explore changes in microvascular tone during a contralateral cold pressor test and to compare the results obtained in healthy subjects and in patients with impaired glucose tolerance (IGT) and type 2 diabetes. Low-amplitude fluctuations of skin temperature in the appropriate frequency ranges were used as a characteristic for the mechanism for vascular tone regulation. In total, 13 adults with type 2 diabetes aged 40-67 years and 18 adults with IGT aged 31-60 years participated in this pilot study. The control group included 12 healthy men and women aged 39-60 years. The response to the cold pressor test in patients with type 2 diabetes and with IGT differs essentially from that of healthy subjects in the endothelial frequency range. Endothelial dysfunction occurs in the preclinical stage of diabetes and manifests, in particular, as a disturbance of the endothelial part of vascular tone regulation.

Personalized foot orthoses with embedded temperature sensing: Proof of concept and relationship with activity

Plantar foot surface temperature has been identified as a clinically relevant physiological variable. Embedding sensors in foot orthoses (FOs) may allow long term monitoring of these temperatures, with compliance via the detection of periods of activity being a potential clinical utilization. This study aimed to test novel designs for FOs with embedded sensing that were produced via additive manufacturing and determine if foot temperature measurements could be used to detect periods of increased activity. FOs with embedded temperature sensors were developed and tested in 10 healthy participants over four day wear periods. Activity monitoring was used to estimate energy expenditure during testing. A threshold-based algorithm was developed to identify time periods of high activity from foot temperature data. Group differences in estimated energy expenditure between time periods below and above the threshold were significant in both the training and validation sets (p<0.001). Significant differences were also seen at individual participant level (p<0.001 in all cases). These results demonstrate the feasibility of using FOs with embedded sensing to monitor plantar surface foot temperatures during normal daily activities and for extended periods and show that periods of increased activity can be identified using foot temperature data.

Evaluation of the clinical efficacy of multiple lower-extremity nerve decompression in diabetic peripheral neuropathy

OBJECTIVE

To evaluate the value of high-resolution ultrasonography and neural electrophysiology in early diagnosis, operative opportunity selection, and clinical effect assessment of DPN.

METHODS

Five hundred and sixty patients with diabetic peripheral neuropathy (DPN) were treated with DELLON surgical nerve decompression in our hospital in the past 5 years. Before and after 18 months surgery, the tests of the Toronto clinical scoring system, high-resolution ultrasonography, QST, and Nerve Conduction Velocity (NCV) were evaluated in all cases. The control group included 40 diabetic patients in the same age range but without DPN.

RESULTS

Ultrasonographic images revealed an apparently normal proximal common peroneal nerve, tibial nerve marked swelling, enlarged, and hypoechogeneity with loss fascicular pattern. The cross-sectional-area, anteroposterior and transverse diameter were measured preoperative and prooperative, and the differences had statistical significance (P < 0.01). NCV-positive cases amount to 74.9% DPN patients in this study and QST-positive cases amount to 90.9% and had significant differences between them (P < 0.05). Postoperative NCV and cold perception threshold significantly increased (P < 0.05) compared with that of the before surgery. Postoperative warm perception threshold (P < 0.01) and vibration perception threshold (P < 0.05) were significantly lower than the preoperative value. NCV was positively correlated with cold perception threshold (r = 0.395, P < 0.01), and negatively correlated with warm perception threshold (r = - 0.387, P < 0.01) and vibratory perception threshold (r = - 0.367, P < 0.01). The preoperative TCSS score was 19 points for all the cases, and 420 cases (75%) improved to 10-13 points (P < 0.01).

CONCLUSION

Ultrasonography is capable of depicting these nerves morphological information, with respect to exact location, course, and extent. QST is suitable for early diagnosis of DPN, and abnormal QST is an indication of lower extremity nerve decompression for DPN. The joint use of QST and NCV testing helps surgeons to grasp the timing of surgery. High-resolution ultrasound, QST and NCV testing can also be used as an outcome index for surgical treatment.

Quantitation and composition of cutaneous microbiota in diabetic and nondiabetic men

BACKGROUND

Diabetic foot infections are a leading cause of lower extremity amputations. Our study examines the microbiota of diabetic skin prior to ulcer development or infection.

METHODS

In a case-control study, outpatient males were recruited at a veterans hospital. Subjects were swabbed at 4 cutaneous sites, 1 on the forearm and 3 on the foot. Quantitative polymerase chain reaction (qPCR) with primers and probes specific for bacteria, Staphylococcus species, Staphylococcus aureus, and fungi were performed on all samples. High-throughput 16S ribosomal RNA (rRNA) sequencing was performed on samples from the forearm and the plantar aspect of the foot.

RESULTS

qPCR analysis of swab specimens from 30 diabetic subjects and 30 control subjects showed no differences in total numbers of bacteria or fungi at any sampled site. Increased log concentrations of Staphylococcus aureus, quantified by the number of nuc gene copies, were present in diabetic men on the plantar aspect of the foot. High-throughput 16S rRNA sequencing found that, on the foot, the microbiota in controls (n = 24) was dominated by Staphylococcus species, whereas the microbiota in diabetics (n = 23) was more diverse at the genus level. The forearm microbiota had similar diversity in diabetic and control groups.

CONCLUSIONS

The feet of diabetic men had decreased populations of Staphylococcus species, increased populations of S. aureus, and increased bacterial diversity, compared with the feet of controls. These ecologic changes may affect the risk for wound infections.

Coming events cast their shadows before: detecting inflammation in the acute diabetic foot and the foot in remission

The incidence of diabetic foot complications, most notably wounds, is increasing worldwide. Most people who present for care of a foot wound will become infected. Globally, this results in one major amputation every 30 seconds with over 2500 limbs lost per day. Presently, clinicians assess circulation, neuropathy and plantar pressures to identify the risk of foot ulceration. Several studies have suggested prevention of foot ulcers by identifying individuals at high risk and treating for lower extremity complications. Our group has proposed several diagnostics as well as prevention strategies, especially thermography and thermometry for management of patients with diabetic foot complications. These strategies employ non-invasive assessment of inflammation for acute as well as chronic care for the foot, with the intent to prevent ulceration/re-ulceration and subsequent traumatic amputations. The authors' review some important clinical studies and ongoing research in this area, with the long-term goal to further the role of thermography and thermometry in clinical care for the diabetic foot.

Disturbed subjective sleep characteristics in adult patients with long-standing type 1 diabetes mellitus

AIMS/HYPOTHESIS

Decreased sleep duration and/or impaired sleep quality negatively influence glucoregulation. The aim of this study was to assess subjective sleep characteristics in patients with type 1 diabetes, to relate sleep characteristics to long-term glycaemic control and to assess possible risk factors for impaired sleep.

METHODS

We studied 99 adult patients with type 1 diabetes (55 men, 44 women, duration of diabetes 26.9 ± 1.2 years) and 99 age-, sex- and BMI-matched non-diabetic controls. Subjective sleep characteristics were assessed by validated questionnaires, i.e. Pittsburgh Sleep Quality Index, Epworth Sleepiness Scale and the Berlin Questionnaire. Glucoregulation was assessed by HbA(1c) values. Clinical variables were obtained from medical charts. Depression was assessed by the Hospital Anxiety and Depression Scale (HADS). Peripheral polyneuropathy was assessed by neurological examination and quantitative sensory testing.

RESULTS

Of the patients with type 1 diabetes, 35% had subjective poor sleep quality compared with 20% of the control participants (p = 0.021). A higher proportion of the patients with type 1 diabetes were at increased risk for obstructive sleep apnoea (OSA) (17.2% vs 5.1%, p = 0.012). There was no significant association between individual sleep characteristics and HbA(1c) values. On logistic regression analysis, the HADS depression score, presence of peripheral polyneuropathy, habitual snoring and other sleep disturbances (e.g. hypoglycaemia) were independently associated with poor sleep quality.

CONCLUSIONS/INTERPRETATION

Adult patients with long-standing type 1 diabetes mellitus have disturbed subjective sleep quality and a higher risk for OSA compared with control participants. Subjective sleep disturbances are part of the complex syndrome of long-standing type 1 diabetes.

Foot temperature in healthy individuals: effects of ambient temperature and age

BACKGROUND

Patient complaints of excessively warm or cold feet are common in medical practice. Such symptoms can be caused by underlying vascular or neurologic disease, and measurement of foot temperature during daily activity and sleep could provide a deeper understanding of their actual thermal basis.

METHODS

We used a Thermochron iButton to assess surface foot temperature variation and its relationship to ambient temperature during the day with activity and at night during sleep in 39 healthy individuals aged 18 to 65 years in a temperate region of the United States. We simultaneously used actigraphy to record leg movement.

RESULTS

We identified a mean +/- SD awake temperature of 30.6 degrees +/- 2.6 degrees C and asleep temperature of 34.0 degrees +/- 1.8 degrees C, with values reaching as low as 15.9 degrees C in the winter and as high as 37.5 degrees C in the summer. Foot temperature was found to be independent of foot movement or sex; however, there was, as expected, a strong association between foot temperature and ambient temperature (r = .59, P < .001). Several measures of foot temperature variation demonstrated a significant or near-significant reduction with increasing age, including the Euclidean distance (r = -.38, P = .02) for awake periods and the variance (r = -.30, P = .06) during sleep.

CONCLUSIONS

These results provide data on the normal variation of foot temperature in individuals living in a temperate climate and demonstrate the potential use of Thermochron iButton technology in clinical contexts, including the evaluation of patients with excessively warm or cold feet.

Cold exposure exacerbates the development of diabetic polyneuropathy in the rat

Diabetic polyneuropathy (DPN) and cold-induced nerve injury share several pathogenic mechanisms. This study explores whether cold exposure contributes to the development of DPN. Streptozotocin-induced diabetic rats and controls were exposed to a room temperature (23°C) or cold environment (10°C). H-reflex, tail and sciatic motor, and sensory nerve conduction studies were performed. Analyses of sural nerve, intraepidermal nerve fibers, and skin and nerve nitrotyrosine ELISAs were performed. Diabetic animals exposed to a cold environment had an increased H-reflex four weeks earlier than diabetic room temperature animals (P = .03). Cold-exposed diabetic animals also had greater reduction in motor conduction velocities at 20 weeks (P = .017), decreased skin nerve fiber density (P = .037), and increased skin nitrotyrosine levels (P = .047). Cold exposure appears to hasten the development of DPN in the rat STZ model of diabetes. These findings support that further study into the relationship between ambient temperature and DPN is warranted.