The skin in diabetes mellitus

A narrative review of the measurement methods for biomechanical properties of plantar soft tissue in patients with diabetic foot

This article provides an overview of the development history and advantages and disadvantages of measurement methods for soft tissue properties of the plantar foot. The measurement of soft tissue properties is essential for understanding the biomechanical characteristics and function of the foot, as well as for designing and evaluating orthotic devices and footwear. Various methods have been developed to measure the properties of plantar soft tissues, including ultrasound imaging, indentation testing, magnetic resonance elastography, and shear wave elastography. Each method has its own strengths and limitations, and choosing the most appropriate method depends on the specific research or clinical objectives. This review aims to assist researchers and clinicians in selecting the most suitable measurement method for their specific needs.

The compressive, shear, biochemical, and histological characteristics of diabetic and non-diabetic plantar skin are minimally different

Diabetes is associated with lower limb co-morbidities, including ulceration and subsequent amputation. As a systemic disease, diabetes affects the microstructure of soft tissues, and material microstructural changes are known to affect the macroscale mechanics. However, the associations between diabetes-related disruptions to essential microstructural components and mechanical changes in plantar skin with diabetes has not been thoroughly characterized. Plantar skin specimens were collected from four diabetic and eight non-diabetic donors at six plantar locations (hallux; first, third, and fifth metatarsals; lateral midfoot; calcaneus) from matched pairs. Mechanical testing was performed on fresh frozen specimens from one foot, and histomorphological measurement and biochemical quantification were performed on specimens from the other foot. Mechanical (compressive and shear moduli and viscoelastic slopes) and biochemical/histological (total quantity of collagen and elastin; dermal and epidermal thickness) parameters were correlated using linear mixed effects regression. There were no significant differences by disease state. Skin thicknesses were positively correlated with initial compression modulus and all three shear moduli. The final compressive modulus was significantly lower at the third metatarsal than the fifth metatarsal, lateral midfoot, and calcaneus, while the final shear modulus was significantly higher at the calcaneus than at the hallux, first, and third metatarsals. Epidermal thickness was significantly higher at the calcaneus compared to all other locations. While differences were not significant by disease state, the strong differences by locations and significant but weak correlations between skin thickness and mechanics can inform future research to understand the mechanism of ulcer formation in the diabetic foot.

Feasibility of a home-based foot-ankle exercise programme for musculoskeletal dysfunctions in people with diabetes: randomised controlled FOotCAre (FOCA) Trial II

This study sought to assess the feasibility of design, adherence, satisfaction, safety and changes in outcomes followed by a home-based foot–ankle exercise guided by a booklet in individuals with diabetic peripheral neuropathy (DPN). 20 participants were allocated usual care [control group (CG)] or usual care plus home-based foot–ankle exercises [intervention group (IG)] for 8 weeks. For feasibility, we assessed contact, preliminary screening and recruitment rates, adherence, and using a 5-point Likert scale to satisfaction and safety of the booklet. In the IG, we assessed preliminary changes in DPN symptoms, DPN severity (classified by a fuzzy model) and foot–ankle range of motion between baseline and Week 8. In the first 20 weeks, 1310 individuals were screened for eligibility by phone contact. Contact rate was 89% (contacted participants/20w), preliminary screening success 28% (participants underwent screening/20w), and recruitment rate 1.0 participants/week (eligible participants/20w). The recruitment rate was less than the ideal rate of 5 participants/week. The adherence to the exercises programme was 77%, and the dropout was 11% and 9% for the IG and CG, respectively. In the IG, participants’ median level of satisfaction was 4 (IQR: 4–5) and perceived safety was 3 (IQR: 3–5). IG significantly decreased the DPN severity (p = 0.020), increased hallux relative to forefoot (first metatarsal) range of motion (ROM) (p < 0.001) and decreased maximum forefoot relative to hindfoot (midfoot motion) dorsiflexion during gait (p = 0.029). The home-based programme was feasible, satisfactory, safe and showed preliminary positive changes in DPN severity and foot motion during gait.

Trial Registration ClinicalTrials.gov, NCT04008745. Registered 02/07/2019. https://clinicaltrials.gov/ct2/show/NCT04008745.

Comparing skin characteristics and molecular markers of xerotic foot skin between diabetic and non-diabetic subjects: An exploratory study

BACKGROUND

Xerosis cutis of the feet is one of the most common skin conditions among type 2 diabetics. Whether skin dryness among diabetic patients is different from 'general' skin dryness is unclear. The overall aim was to compare the structure, function and molecular markers of dry and cracked foot skin between diabetics and non-diabetics.

METHODS

The foot skin of 40 diabetics and 20 non-diabetics was evaluated. A clinical assessment of skin dryness was performed and transepidermal water loss, stratum corneum hydration, skin surface pH, epidermal thickness, skin roughness, elasticity and structural stiffness were measured. Ceramides, natural moisturizing factors, histamines, proteins and molecular markers of oxidative stress were analyzed based on a non-invasive sampling method for collection of surface biomarkers.

RESULTS

The mean number of superficial fissures in the diabetic group was nearly three times higher than in the non-diabetic group (11.0 (SD 6.2) vs. 3.9 (SD 4.2)). The skin stiffness was higher in the diabetic group and the values of almost all molecular markers showed considerably higher values compared to non-diabetics. Malondialdehyde and glutathione were lower in the diabetic sample.

CONCLUSIONS

The high number of superficial fissures may be based on an increased stiffness of dry diabetic foot skin combined with different concentrations of molecular markers in the stratum corneum compared to dry foot skin of non-diabetics.

Skin Hydration Level as a Predictor for Diabetic Wound Healing: A Retrospective Study

BACKGROUND

In the diabetic foot, the skin may crack and develop fissures, potentially increasing vulnerability to ulceration and infection. Therefore, maintaining adequate skin hydration may be crucial for diabetic wound healing. However, no clinical study has addressed this issue. This study aimed to determine and compare the effect of the skin hydration level on diabetic wound healing with that of the tissue oxygenation level, which is recognized as the most reliable parameter in predicting diabetic wound healing.

METHODS

This retrospective study included 263 diabetic patients with forefoot ulcers. Skin hydration and transcutaneous oxygen pressure data collected before and after percutaneous transluminal angioplasty were analyzed. Skin hydration and tissue oxygenation were graded as poor, moderate, or acceptable. Wound healing outcomes were graded as healed without amputation, minor amputation, or major amputation. Wound healing outcomes were compared using four parameters: skin hydration at baseline, transcutaneous oxygen pressure at baseline, post-percutaneous transluminal angioplasty skin hydration, and post-percutaneous transluminal angioplasty transcutaneous oxygen pressure.

RESULTS

Each of the four parameters exhibited statistically significant correlations with wound healing outcomes. In the concurrent analysis of both skin hydration and transcutaneous oxygen pressure, skin hydration was a dominant parameter (p = 0.0018) at baseline, whereas transcutaneous oxygen pressure was a dominant parameter (p < 0.0001) following percutaneous transluminal angioplasty.

CONCLUSIONS

Skin hydration level might be a useful predictor for diabetic wound healing. In particular, the skin hydration level before recanalization was found to be superior to transcutaneous oxygen pressure in predicting wound healing.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Risk, III.

Histomorphological and biochemical properties of plantar soft tissue in diabetes

BACKGROUND

Diabetes results in pathophysiological changes, leading to tissue that is unable to withstand and adapt to the same loads, resulting in breakdown. Certain locations are more susceptible to breakdown, yet differences between locations are largely not well understood. The authors performed a histological and biochemical analysis of isolated plantar adipose tissue at six relevant locations.

METHODS

Tissue from six plantar locations (hallux, first, third and fifth metatarsal heads, lateral midfoot and calcaneus) was taken from fresh cadaveric feet of older diabetic and older non-diabetic intact donors. Histomorphological and biochemical analysis of isolated plantar tissue from both diabetic and non-diabetic feet at six relevant locations was performed.

RESULTS

The main differences found between diabetic and non-diabetic tissue were in the thickness of the septal walls and the elastin content. Diabetic tissue had significantly thicker septal walls and an increased elastin concentration. When comparing the calcaneus to other locations, although there were no differences found in the thickness of the septal walls of diabetic tissue, elastin content was lower in the calcaneous tissue compared to the non-calcaneus sites.

CONCLUSIONS

Modifications in the structural and biochemical properties could translate to changes in the mechanical properties. This information could lead to an understanding of how the structural and biochemical changes result in an increase in susceptibility of tissue to breakdown with load at the different locations of the foot.

The contribution of a directional preference of stiffness to the efficacy of prophylactic sacral dressings in protecting healthy and diabetic tissues from pressure injury: computational modelling studies

The sacral region is the most common site for pressure injuries (PIs) associated with lying in bed, and such sacral PIs often commence as deep tissue injuries (DTIs) that later present as open wounds. In complex patients, diabetes is common. Because, among other factors, diabetes affects connective tissue stiffness properties, making these tissues less able to dissipate mechanical loads through physiological deformations, diabetes is an additional biomechanical risk factor for PIs and DTIs. A preventive measure with established successful clinical outcomes is the use of sacral prophylactic dressings. The objective of this study has been to expand our previous work regarding the modes of action and biomechanical efficacy of prophylactic dressings in protecting the soft tissues adjacent to the sacrum by specifically examining the role of a directional stiffness preference (anisotropy) of the dressing while further accounting for diabetic tissue conditions. Multiple three-dimensional anatomically detailed finite element (FE) model variants representing diabetic tissue conditions were used, and tissue loading state data were compared with healthy tissue simulations. We specifically compared soft tissue exposures to elevated internal shear stresses and strain energy densities (SED) near the sacrum during supine weight bearing on a standard (foam) hospital mattress without a dressing, with a prophylactic dressing lacking directional stiffness preferences and with an anisotropic dressing. Our results have clearly shown that an anisotropic dressing design reduces the peak tissue stresses and exposure to sustained tissue deformations in both healthy and diabetic cases. The present study provides additional important insights regarding the optimal structural and material design of prophylactic dressings, which in turn, informs clinicians and decision makers regarding beneficial features.

Use of a urea, arginine and carnosine cream versus a standard emollient glycerol cream for treatment of severe xerosis of the feet in patients with type 2 diabetes: a randomized, 8 month, assessor-blinded, controlled trial

BACKGROUND

No long-term data are available regarding the effects of emollients in treating severe foot skin xerosis in patients with diabetes.

STUDY AIM

We evaluated the efficacy of 8 month urea, arginine and carnosine cream (UC) in comparison with a glycerin-based emollient cream (SEC) in type 2 patients with diabetes who had severe foot xerosis.

SUBJECTS AND METHODS

We assessed the effect of UC and SEC on skin hydration in a randomized, assessor-blinded study in 50 patients treated with UC (N = 25) or SEC (N = 25) for 32 weeks with a twice daily application. Primary outcomes were a 9 point Xerosis Assessment Scale (XAS) score and a 4 point Overall Cutaneous Score (OCS), evaluated at baseline and after 4, 12 and 32 weeks. Skin hydration and desquamation were also objectively evaluated by means of a bio-impedance skin analysis device (Hydr8 * ) at baseline and at week 32.

RESULTS

UC induced greater hydration than SEC (p = 0.001) with a 91% reduction at week 32 in XAS score vs. baseline. After 4 weeks, compared with the SEC treated group, the XAS score in the UC treated group was significantly lower. OCS was reduced by 27% from baseline to end of the study in the UC group, and increased by 8% in the SEC group (p = 0.02; between groups). At month 8, skin hydration and desquamation evaluated by the digital skin analysis system statistically improved in UC treated subjects in comparison with baseline and SEC group values. This study was not double-blind. In order to overcome this problem we performed an assessor-blinded evaluation of the primary endpoints and used an objective measurement tool for skin hydration and desquamation assessment.

CONCLUSION

Using a urea, arginine and carnosine cream for 8 months increases skin hydration and improves skin dryness in type 2 diabetic patients in comparison with a glycerol-based emollient cream, with a greater efficacy observed as early as 4 weeks into treatment.

Effect of viscoelastic properties of plantar soft tissues on plantar pressures at the first metatarsal head in diabetics with peripheral neuropathy

Diabetic foot ulcers are one of the most serious complications associated with diabetes mellitus. Current research studies have demonstrated that biomechanical alterations of the diabetic foot contribute to the development of foot ulcers. However, the changes of soft tissue biomechanical properties associated with diabetes and its influences on the development of diabetic foot ulcers have not been investigated. The purpose of this study was to investigate the effect of diabetes on the biomechanical properties of plantar soft tissues and the relationship between biomechanical properties and plantar pressure distributions. We used the ultrasound indentation tests to measure force-deformation relationships of plantar soft tissues and calculate the effective Young's modulus and quasi-linear viscoelastic parameters to quantify biomechanical properties of plantar soft tissues. We also measured plantar pressures to calculate peak plantar pressure and plantar pressure gradient. Our results showed that diabetics had a significantly greater effective Young's modulus and initial modulus of quasi-linear viscoelasticity compared to non-diabetics. The plantar pressure gradient and biomechanical properties were significantly correlated. Our findings indicate that diabetes is linked to an increase in viscoelasticity of plantar soft tissues that may contribute to a higher peak plantar pressure and plantar pressure gradient in the diabetic foot.

An urea, arginine and carnosine based cream (Ureadin Rx Db ISDIN) shows greater efficacy in the treatment of severe xerosis of the feet in Type 2 diabetic patients in comparison with glycerol-based emollient cream. A randomized, assessor-blinded, controlled trial

BACKGROUND

Xerosis is a common skin disorder frequently observed in diabetic patients. An effective hydration of foot skin in diabetics is a relevant preventive strategy in order to maintain a healthy foot. Urea is considered an effective hydrating and emollient topical product. The aim of the present study was to evaluate the efficacy of topical urea 5% with arginine and carnosine (Ureadin Rx Db, ISDIN Spain) (UC) in comparison with glycerol-based emollient topical product (Dexeryl, Pierre Fabre) (EC), in Type 2 diabetic patients.

METHODS

We assessed the effect of UC on skin hydration in a randomized, evaluator-blinded comparative study in 40 type II diabetic patients, aged 40-75 years, treated with UC or the comparator for 28 days with a twice-daily application. The principal outcomes were the Dryness Area Severity Index (DASI) Score and the Visual Analogue Score (VAS) for skin dryness evaluated at baseline and at the end of study period by an investigator unaware of treatment allocation.

RESULTS

UC induced significantly greater hydration than EC with an 89% reduction in DASI score (from 1.6 to 0.2; p < 0.001) in comparison with baseline values. After 4 weeks, compared with the control group, DASI score in UC treated group was significantly lower (0.2 vs. 1.0; p = 0.048). VAS score (high values mean better hydration) significantly increased in both groups during treatment. VAS score at the end of treatment period was significantly higher in UC group in comparison with EC group (9.8 vs. 8.2; p = 0.05).

CONCLUSION

Application of urea 5%, arginine and carnosine cream increases skin hydration and alleviates the condition of skin dryness in Type 2 diabetic patients in comparison with a control glycerol-based emollient product. (Dutch Trials Register trial number 3328).

Histomorphological evaluation of diabetic and non-diabetic plantar soft tissue

BACKGROUND

Diabetic foot ulceration has a complex and multifactorial etiology and can involve changes in the pathophysiology of the plantar soft tissue. In the current study, histomorphological analyses of diabetic and non-diabetic plantar tissue were performed. It was hypothesized that the diabetic tissue would have thicker skin (epidermis and dermis), less interdigitation between the dermis and epidermis, thicker elastic septa and decreased adipose cell size.

MATERIALS AND METHODS

Two locations of the foot (the heel and the first metatarsal) were examined, both of which have been reported to be locations with a high incidence of ulceration. Stereological methods and quantitative morphological techniques were used to evaluate the skin thickness, interdigitation index, elastic septae thickness and adipocyte cell size.

RESULTS

The diabetic donors had a greater body mass index (BMI) than the non-diabetic donors. The diabetic tissue had significantly thicker elastic septae and dermis. However, no significant difference was observed in the interdigitation index or adipocyte size.

CONCLUSION

These findings demonstrate that morphological changes can be evaluated histologically to give a better understanding of the pathological changes in the plantar soft tissue with diabetes. These evaluations can then be associated with biomechanical changes that occur in diabetes to provide new insight into how microstructural changes can alter macroscopic properties.

CLINICAL RELEVANCE

An understanding of the histomorphological changes in the soft tissue in relationship to the location on the foot could help to explain the biomechanical changes that occur in diabetes and the subsequent increase in susceptibility to breakdown.

Diabetes mellitus

Dermatologic problems are common in diabetes, with approximately 30% of patients experiencing some cutaneous involvement during the course of their illness. Skin manifestations generally appear during the course of the disease in patients known to have diabetes, but they may also be the first presenting sign of diabetes or even precede the diagnosis by many years. The skin involvement can be autoimmune in nature, such as acanthosis nigricans, necrobiosis lipoidica, diabetic dermopathy, scleredema, and granuloma annulare, or infectious in the form of erythrasma, necrotizing fasciitis, and mucormycosis. Pharmacologic management of diabetes, in addition, can also result in skin changes, such as lipoatrophy and lipohypertrophy, at the site of injection of insulin, and oral antidiabetic agents can cause multiple skin reactions as adverse effects. The management of these cutaneous manifestations is tailored according to the underlying pathophysiology, but a tight control of blood glucose is a prerequisite in all management strategies.

Computed tomography to visualize and quantify the plantar aponeurosis and flexor hallucis longus tendon in the diabetic foot

BACKGROUND

The purposes of this report were to describe a three-dimensional computed tomography based method to visualize and quantify the thickness of the plantar aponeurosis and flexor hallucis longus tendon and determine the reliability of thickness measures. Given reliable measures, a secondary purpose was to compare plantar aponeurosis and flexor hallucis longus thickness in subjects with diabetes mellitus and peripheral neuropathy to an age and weight matched group without diabetes.

METHODS

CT data from 16 people with diabetes mellitus and peripheral neuropathy (mean age 55.2 (SD 10.5), 4 female, 12 male, body mass index 31.7 (SD 7.6)) and 10 people without diabetes mellitus (mean age 53.8 (SD 9.1), 2 female, 8 male, body mass index 37.0 (SD 8.6)) were analyzed. Length and thickness of the plantar aponeurosis and flexor hallucis longus tendon were measured twice for five subjects from each group in a blinded single observer reliability study.

FINDINGS

The average mean difference of the linear measurements was 0.12 mm (average SD=1.00 mm). Significant differences for measures of plantar aponeurosis thickness (p=0.044) were found between diabetic, 4.2 mm (SD 0.9), and control groups, 3.6 mm (SD 0.8), and approached significance for tendon thickness measured at the midfoot (diabetic group 4.8 mm (SD 0.8), control group 4.3 mm (SD 0.8), p=0.051).

INTERPRETATION

CT was shown to be a reliable imaging technique for visualizing and quantifying soft tissue structures in diabetic feet. The methods and the quantitative description of the plantar aponeurosis and tendon thickness reported in this paper may be useful to those developing three-dimensional computational models of the foot.

[Diffusion of ulcers in the diabetic foot is promoted by stiffening of plantar muscular tissue under excessive bone compression]

The abnormally elevated plantar pressures under the bony prominences of the diabetic foot (mainly under the medial metatarsal heads and calcaneus) were associated with intensified internal stresses in the deep soft tissues padding these bones. In this study, we tested changes in mechanical properties of muscular tissue after exposure to the internal stress levels typically developing under the first and second metatarsal heads in the load bearing diabetic foot (40-80 KPa). The gracilis muscles of anesthetized rats were subjected to constant external pressures of 35 and 70 KPa for 2 h, which caused average internal compression stresses of 40 and 80 KPa, respectively, within the living gracilis. The animals were then killed and the tangent elastic moduli of the harvested gracilis were measured in uniaxial tension at strains of 2.5%, 5% and 7.5%. Tangent moduli of gracilis muscles exposed to internal compression of 40-80 KPa in vivo ( n=6) were 1.6-fold stiffer ( p<0.05) than those of controls ( n=6). These abnormally stiff mechanical properties were incorporated into a finite element (FE) model of the plantar tissue under the second ray of the foot, and were shown to increase the magnitude of deep internal stresses and project elevated stresses to larger regions. Hence, the integration of animal model data with FE simulations indicates a mechanism of plantar tissue deterioration in the diabetic foot, where muscles exposed to critical stresses respond with increased stiffness which then further intensifies the deep plantar stresses. This suggests a new positive feedback mechanism for the diffusion of ulcers and the atrophy of intrinsic plantar muscles in the diabetic foot, where the injury spreads from deep muscles to the skin surface by an evolving mechanical stress wave.

Use of a Torque-Range-of-Motion device for objective differentiation of diabetic from normal feet in adults

BACKGROUND

The ability of the foot and ankle complex to act as an energy absorber is reflected in its viscoelastic properties. The Torque-Range-of-Motion (TROM) device was designed to provide an effective objective assessment of foot and ankle passive mechanical function. The hypothesis of this study was that mechanical parameters derived from passive TROM curves of otherwise normal feet of adults with diabetes would be significantly different from those of adults without diabetes.

METHODS

The TROM device is a single-degree-of-freedom hinge transducer system that is manually rotated through plantarflexion and dorsiflexion. The device was rotated manually with the muscles relaxed during a 50-second data acquisition period. A strain gauge provided the torque signal and a precision single-turn potentiometer provided plantarflexion-dorsiflexion angle to a two-channel portable data acquisition system. With the TROM device connected to a computer, input for instantaneous torque and range of motion was acquired and displayed as angle (degrees) versus torque (Newton-meters) on an output screen. The period provided sufficient data to average 16 to 20 cycles of motion. The study included 41 feet in adults without diabetes and 42 age-matched feet in adults with diabetes but no known foot problems.

RESULTS

For a probability level of.0001 there were significant differences in hysteresis area (normal: 91.1 +/- 46.9 Nm-deg and diabetic: 161.7 +/- 65.7 Nm-deg) and both dorsiflexion (normal: 0.4 +/- 0.1 Nm/deg and diabetic: 0.9 +/- 0.3 Nm/deg) and plantarflexion stiffness (normal: 0.3 +/- 0.1 Nm/deg and diabetic: 0.7 +/- 0.3 Nm/deg).

CONCLUSIONS

The feet of adults with diabetes absorb more energy during cyclic motion (thus must dissipate more energy per cycle) and are stiffer in the terminal regions (where muscle-tendon-ligament properties prevail) than are the feet of adults without diabetes. These results suggest that this passive TROM method may be a sensitive, objective measurement of the viscoelastic properties of the foot and ankle, which may be an early indicator of diabetic patients who are at risk for the development of foot problems.

Plantar soft tissue loading under the medial metatarsals in the standing diabetic foot

Diabetes mellitus (type 2) is the most frequent cause of non-traumatic lower-limb amputations. The major cause of impairment to the feet of diabetics is persistent hyperglycemia, potentially leading to peripheral neuropathy as well as to pathological changes in plantar soft tissue, which stiffen its structure and diminish its ability to effectively distribute foot-ground contact loads. In this study, a computational model of the foot structure in the standing position was utilized to evaluate stress distributions in plantar soft tissue under the medial metatarsal heads of simulated diabetic versus normal feet. The model comprises five anatomic planar cross-sections in the directions of the foot rays, which were solved for internal stresses under static ankle joint reaction (300 N) and triceps surae muscle forces (150 N) using the finite element method. Tissues were assumed to be homogenous, isotropic and elastic materials, with nonlinear stress-strain relations for the ligaments, fascia and plantar tissue. The model revealed significant tension stress concentrations (90-150 KPa) in the plantar pad of the simulated diabetic forefoot: they were four times the normal maximum stress under the first metatarsal head and almost eight times the normal maximum stress under the second metatarsal head. It was shown that with increased severity of stiffening of the plantar pad, as related to glucose-exposure, peak forefoot contact stresses may rise by 38 and 50% under the first and second metatarsal heads, respectively. The increase in averaged (von Mises) internal stresses within the plantar soft tissue is even more pronounced, and may rise by 82 and 307% for the tissue under the first and second metatarsal heads, respectively. These results, which conform to experimental data gathered over the last two decades, suggest that the process of injury in diabetic feet is very likely to initiate not on the skin surface, but in deeper tissue layers, and the tissues underlying the distal bony prominences of the medial metatarsals are the most vulnerable ones.

Ultrasonography of plantar soft tissues thickness in young people with diabetes

AIMS

The aims of this study were to examine soft tissue changes in the skin and plantar aponeurosis of young people with Type 1 diabetes mellitus (T1DM) and to evaluate any relationship between any soft tissue changes, arch length, limited joint mobility (LJM) and plantar pressure.

METHODS

The thickness of the skin on the plantar surface of the foot and plantar aponeurosis were examined using ultrasound in 216 young people with diabetes and 57 controls. Foot length, arch length, joint mobility, peak pressure and pressure time integrals were evaluated.

RESULTS

Skin was not significantly thicker in the diabetic subjects. The plantar aponeurosis was significantly thicker in the diabetic subjects and was associated with foot size, male gender and subtalar joint (ST) LJM (P < 0.01). Males were nearly three times more likely to have thickened plantar aponeurosis.

CONCLUSION

Soft tissue thickening in young people with T1DM affects the deeper structures on the plantar surface of the foot rather than the skin. Thickening of the plantar aponeurosis was associated with LJM at the ST joint and male gender, but was not associated with plantar pressure or arch height changes. Plantar aponeurosis thickening does not appear to alter foot mechanics in young people with T1DM.

Cutaneous manifestations of diabetes mellitus

Diabetes is a common disease with many cutaneous manifestations encountered by dermatologists. Diabetes and the skin may be linked by association (e.g., necrobiosis lipoidica); infection; diabetic complication (e.g., neuropathic ulcer); or treatment reaction. Review of recent studies and reports focuses on pathogenesis and treatment of these many diabetic cutaneous changes.

Effect of parsley (Petroselinum crispum) on the skin of STZ induced diabetic rats

Parsley (Petroselinum crispum) is one of the medicinal herbs used by diabetics in Turkey and it has been reported to reduce blood glucose. The purpose of this study therefore was to investigate the effect of feeding parsley on diabetes induced impairments in rat skins. Uncontrolled induced diabetes caused significant increases in nonenzymatic glycosylation of skin proteins, lipid peroxidation and blood glucose. Administration of parsley extract did not inhibit these effects except for the increase in blood glucose. SDS-polyacrylamide gel electrophoresis revealed no significant differences in any protein bands between any of the groups.

Two-dimensional stress-relaxation behavior of human skin as influenced by non-enzymatic glycation and the inhibitory agent aminoguanidine

In order to simulate the in vivo stress alterations of diabetic skin in an in vitro model, we examined the viscoelastic properties of long-term glycated human skin samples. Since skin is subjected to biaxial tension, we used two-dimensional multiaxial testing which better reflects the in vivo situation than the uniaxial testing mode. For native skin samples from the abdominal region we found a direction-dependent elastic stress strain behavior. The viscous stress component was separated from the elastic stress component by relaxation tests at consecutive incremental steps of radial strains. We hypothesize that glycation-induced changes in the tissue stiffness are generated in a direction-dependent mode. A marked increase of the direction-dependent stiffness was found upon long-term incubation with glucose-6-phosphate. This increase was statistically significant for the maximum principal elastic stress component which was highly correlated with the degree of non-enzymatic collagen modification. The viscous fractions obtained from two-dimensional relaxation tests at consecutive radial strains were inversely correlated with non-enzymatic modification. Only at 30% radial strain a significant decrease of the viscous fraction engendered by glucose-6-phosphate was observed together with a direction-dependent significant increase of the expectation value of the time constant. The biomechanical and biochemical effects of long-term glycation could be partially reversed by aminoguanidine, a potential therapeutic agent for patients with diabetes mellitus. Our findings suggest that additional cross-links generated by long-term glycation cause two-dimensional biomechanical alterations in human skin, which can be unequivocally detected by multiaxial testing.

Skin lesions in diabetes mellitus: prevalence and clinical correlations

With the aim to assess the prevalence and the main clinical correlations of skin lesions in diabetes mellitus, 457 diabetic subjects consecutively attending an outpatient clinic underwent a dermatological examination. Neurovascular foot lesions were excluded. Thirty-five of 64 IDDM patients (54%) had skin alterations mainly consisting of vitiligo (9% of all patients), psoriasis (9%) and eczema (8%). The most frequent skin lesions observed in 240/393 NIDDM subjects (61%) were represented by infections (20% of all patients) and diabetic dermopathy (12.5%), while other lesions were not common. NIDDM patients with skin infections had a worse metabolic control, and those with diabetic dermopathy had a greater prevalence of neuropathy and large vessel disease than patients without skin lesions. These data show that the prevalence of skin diseases in a large, unselected diabetic population is higher than expected and indicate that, in most cases, a careful dermatological examination and a better metabolic control are needed in order to improve quality of life in these patients.

Lack of acidic fibroblast growth factor activation by heparan sulfate species from diabetic rat skin

The glucosaminoglycans isolated from the skin of control and streptozotocin-diabetic rats were fractionated on ion-exchange chromatography into a heparan sulfate (HS)-like and a heparin-like species. In addition, a low sulfated fraction was isolated from the diabetics. The HS and heparin-like fractions isolated from the diabetics (in contrast to the low sulfated fractions) retained high affinity for the acidic (FGF-1) and basic (FGF-2) fibroblast growth factors. In culture, the fractions purified from the control rats and the heparin-like material isolated from the diabetics mediated the biological activity of both FGFs in a dose-dependent manner. By contrast, the diabetic HS-like fractions promoted the biological activity of FGF-2 but not of FGF-1. The results support the idea that the structural motives in HS required for FGF-1 and FGF-2 mediated receptor signalling are different. They may be relevant to the impaired wound healing observed in the disease.

Cutaneous manifestations and consequences of smoking

Cigarette smoking is strongly linked to serious internal diseases such as cancer, cardiovascular disease, and lung disease. However, the external manifestations and consequences of smoking are relatively unknown. Although generally less ominous, the cutaneous manifestations of smoking may be associated with significant morbidity. This article reviews the known adverse effects on the skin of smoking.

Microalbuminuria is associated with limited joint mobility in type I diabetes mellitus

OBJECTIVE

To determine whether limited joint mobility (LJM) is associated with microalbuminuria in type I diabetes mellitus.

METHODS

Joint mobility was measured in a control group of 63 healthy subjects and in 63 type I diabetic patients, older than 18 years (mean 31.7 years, range 18-57), recruited from the outpatient clinic of the Endocrine Unit. Patients with established diabetic nephropathy (proteinuria or increased creatinine) were excluded. Joint mobility was assessed qualitatively with the prayer manoeuvre and quantitatively by measuring the angles of maximal flexion and extension of the fifth and third metacarpophalangeal (MCP) joints and wrist. Diabetic retinopathy was assessed by direct ophthalmoscopy. Urinary albumin excretion (UAE) was determined in at least two 24 hour urine samples.

RESULTS

Joint mobility was limited in diabetic patients compared with control subjects. Diabetic patients with LJM had longer duration of diabetes (12.1 (SD 6.4) years compared with 6.9 (5.7) years; p < 0.001). Joint mobility was limited in patients with retinopathy: prayer manoeuvre was positive in 96.4% of patients with retinopathy, but in only 40.0% of patients with no retinopathy (p < 0.001); mobility of MCP joints and wrist was limited in diabetic patients with retinopathy even when the longer duration of their diabetes was taken into consideration. Microalbuminuria, present in 11 patients (17.5%), was associated with LJM: prayer manoeuvre was positive in 90.9% of patients with microalbuminuria, but in only 57.4% of patients with normal UAE (p < 0.05). Maximal flexion of MCP joints was reduced in patients with microalbuminuria. Microalbuminuria, but not LJM, was associated with risk factors of cardiovascular disease.

CONCLUSION

LJM is associated with microalbuminuria and retinopathy in type I diabetes. The association is independent of age and duration of diabetes.

Cutaneous manifestations of diabetes mellitus

Diabetes mellitus (DM) is a heterogeneous group of disorders characterized by a high serum glucose level and by disturbances of carbohydrate and lipid metabolism. It is estimated that 11 million persons in the United States have DM, 90% of whom have non-insulin-dependent DM. At least 30% of persons with diabetes have some type of cutaneous involvement during the course of their chronic disease. This review classifies the cutaneous findings in DM into four categories: (1) skin diseases with strong to weak association with DM; (2) cutaneous infections; (3) cutaneous manifestations of diabetic complications; and (4) skin reactions to diabetic treatment. Each of these categories is reviewed as well as the pathophysiology of the normal and diabetic basement membrane for a better understanding of the cutaneous manifestations of DM.

Prevalence of dermatophytosis in patients with diabetes

BACKGROUND

Controversy still exists as to whether dermatophytic skin infection is truly more common in patients with diabetes.

OBJECTIVE

The purpose of this study was to determine the true prevalence of dermatophytosis in diabetic patients as compared with a control population.

METHODS

One hundred consecutive diabetic patients were examined for evidence of fungal disease of the skin and compared with nondiabetic, nonimmunocompromised patients. Potassium hydroxide preparation and fungal cultures were obtained from all suspect lesions.

RESULTS

Thirty-one percent of the diabetic population had culture-proven fungal infections compared with 33% of the control group. The organism most commonly isolated was Trichophyton rubrum in both groups, and the feet were the most common site of infection. Candida albicans was more prevalent in the control group, affecting the nails in particular (24% vs 15% in the diabetic patients).

CONCLUSION

This study shows that there does not seem to be an increased prevalence of dermatophytosis in diabetic patients as compared with a control, nondiabetic patient.

Intermittent dietary restriction in eSS diabetic rats. Effects on metabolic control and skin morphology

eSS rats exhibit a non-insulin-dependent diabetic syndrome, significantly influenced by diet. Long-term effects of intermittent dietary restriction were studied in male eSS rats. Experimental animals were fed ad libitum during 48 h and food-deprived the next 24 h (R) while controls (L) of the same strain were freely fed every day. This schedule was maintained from 21 days of age until all rats were sacrificed. R animals were leaner than L rats at 5, 8 and 13 months of age. Moreover, an improved metabolic profile (i.e., lower levels in blood triglycerides, total blood cholesterol, basal blood glucose and blood glucose after an oral glucose load) was found. Histological examination of nuchal skin specimens showed a significant increase of dermal thickness and epidermal hypotrophy in free-fed animals. Collagenous fibers closely packed were found just beneath the dermo-epidermal junction in L rats. This finding was less pronounced in R rats. The above mentioned results suggest that eSS rats would draw advantage from living in environments where food availability is uncertain. The importance of early dietary restrictions in predisposed genotypes appears to be a valuable preventive measure against diabetic evolution and complications.