Helen L. Lutgers

Skin Autofluorescence: A Tool to Identify Type 2 Diabetic Patients at Risk for Developing Microvascular Complications

OBJECTIVE—Skin autofluorescence is a noninvasive measure of the level of tissue accumulation of advanced glycation end products, representing cumulative glycemic and oxidative stress. Recent studies have already shown a relationship between skin autofluorescence and diabetes complications, as well as the predictive value of skin autofluorescence for total and cardiovascular mortality in type 2 diabetes. Our aim was to investigate the predictive value of skin autofluorescence for the development of microvascular complications in type 2 diabetes. RESEARCH DESIGN AND METHODS—At baseline, skin autofluorescence of 973 type 2 diabetic patients with well-controlled diabetes was noninvasively measured with an autofluorescence reader. The aggregate clinical outcome was defined as the development of any diabetes-associated microvascular complication of 881 surviving patients, which was assessed at baseline and at the end of follow-up. Single end points were the development of diabetes-associated retinopathy, neuropathy, and (micro)albuminuria. RESULTS—After a mean follow-up period of 3.1 years, baseline skin autofluorescence was significantly higher in patients who developed any microvascular complication, neuropathy, or (micro)albuminuria but not in those who developed retinopathy. Multivariate analyses showed skin autofluorescence as a predictor for development of any microvascular complication along with A1C, for development of neuropathy along with smoking, and for development of (micro)albuminuria together with sex, A1C, and diabetes duration. Skin autofluorescence did not have predictive value for the development of retinopathy, albeit diabetes duration did. CONCLUSIONS—Our study is the first observation of skin autofluorescence measurement as an independent predictor of development of microvascular complications in type 2 diabetes.

Skin autofluorescence provides additional information to the UK Prospective Diabetes Study (UKPDS) risk score for the estimation of cardiovascular prognosis in type 2 diabetes mellitus

Aims/hypothesisThe UK Prospective Diabetes Study (UKPDS) risk engine has become a standard for cardiovascular risk assessment in type 2 diabetes mellitus. Skin autofluorescence was recently introduced as an alternative tool for cardiovascular risk assessment in diabetes. We investigated the prognostic value of skin autofluorescence for cardiovascular events in combination with the UKPDS risk engine in a cohort of patients with type 2 diabetes managed in primary care.MethodsClinical, UKPDS risk engine and skin autofluorescence data were obtained at baseline in 2001–2002 in the type 2 diabetes group (nu2009=u2009973). Follow-up data concerning fatal and non-fatal cardiovascular events (primary endpoint) were obtained till 2005. Patients were classified as ‘low risk’ when their 10xa0year UKPDS risk score for fatal cardiovascular events was <10%, and ‘high risk’ if >10%. Skin autofluorescence was measured non-invasively with an autofluorescence reader. Skin autofluorescence was classified by the median (i.e. low risk < median, high risk > median).ResultsThe incidence of cardiovascular events was 119 (44 fatal, 75 non-fatal). In multivariate analysis, skin autofluorescence, age, sex and diabetes duration were predictors for the primary endpoint. Addition of skin autofluorescence information to that from the UKPDS risk engine resulted in re-classification of 55 of 203 patients from the low-risk to the high-risk group. The 10xa0year cardiovascular event rate was higher in patients with a UKPDS score >10% when skin autofluorescence was above the median (55.8% vs 38.9%).Conclusions/interpretationSkin autofluorescence provides additional information to the UKPDS risk engine which can result in risk re-classification of a substantial number of patients. It furthermore identifies patients who have a particularly high risk for developing cardiovascular events.

Accumulation of Advanced Glycation End Products, Measured as Skin Autofluorescence, in Renal Disease

Abstract: Advanced glycation end products (AGEs) accumulate during renal failure and dialysis. Kidney transplantation is thought to reverse this accumulation by restoring renal function. Using a noninvasive and validated autofluorescence reader, we evaluated AGE levels in 285 transplant recipients (mean age, 52 years; range, 41 to 60 years), 32 dialysis patients (mean age, 56 years; range, 43 to 65 years), and 231 normal control subjects (mean age, 51 years; range, 40 to 65 years). Measurements in transplant recipients were performed for a mean of 73 months (range, 32 to 143 months) after transplantation. Dialysis patients were on dialysis therapy for a mean of 42 months (range, 17 to 107 months). Fluorescence was significantly increased in dialysis patients compared with normal control subjects (2.8 vs. 2.0 arbitrary units [a.u.], P < .0001). Although fluorescence levels were significantly decreased in transplant recipients compared with dialysis patients (2.5 vs. 2.8 a.u., P < .0001), fluorescence in transplant recipients was higher than in controls (2.5 vs. 2.0 a.u., P < .0001). In transplant recipients, fluorescence correlated positively with the duration of dialysis prior to transplantation (R= 0.21, P < .0001), and negatively with creatinine clearance (R=−0.34, P < .0001). No correlation was found between time after transplantation and fluorescence in transplant recipients (R=−0.10, P= .10). Fluorescence in dialysis patients was positively correlated with duration of dialysis (R= 0.36, P= .042). Our results, like those of others, suggest that kidney transplantation does not fully correct increased AGE levels found in dialysis patients. The increased AGE levels in kidney transplant recipients cannot be explained by the differences in renal function alone. The availability of a simple, noninvasive method (AGE‐Reader) to measure AGE accumulation may be used to monitor AGE accumulation in a clinical setting as well as in a study setting.

Life Expectancy in a Large Cohort of Type 2 Diabetes Patients Treated in Primary Care (ZODIAC-10)

Background Most longitudinal studies showed increased relative mortality in individuals with type 2 diabetes mellitus until now. As a result of major changes in treatment regimes over the past years, with more stringent goals for metabolic control and cardiovascular risk management, improvement of life expectancy should be expected. In our study, we aimed to assess present-day life expectancy of type 2 diabetes patients in an ongoing cohort study. Methodology and Principal Findings We included 973 primary care type 2 diabetes patients in a prospective cohort study, who were all participating in a shared care project in The Netherlands. Vital status was assessed from May 2001 till May 2007. Main outcome measurement was life expectancy assessed by transforming actual survival time to standardised survival time allowing adjustment for the baseline mortality rate of the general population. At baseline, mean age was 66 years, mean HbA1c 7.0%. During a median follow-up of 5.4 years, 165 patients died (78 from cardiovascular causes), and 17 patients were lost to follow-up. There were no differences in life expectancy in subjects with type 2 diabetes compared to life expectancy in the general population. In multivariate Cox regression analyses, concentrating on the endpoints ‘all-cause’ and cardiovascular mortality, a history of cardiovascular disease: hazard ratio (HR) 1.71 (95% confidence interval (CI) 1.23–2.37), and HR 2.59 (95% CI 1.56–4.28); and albuminuria: HR 1.72 (95% CI 1.26–2.35), and HR 1.83 (95% CI 1.17–2.89), respectively, were significant predictors, whereas smoking, HbA1c, systolic blood pressure and diabetes duration were not. Conclusions This study shows a normal life expectancy in a cohort of subjects with type 2 diabetes patients in primary care when compared to the general population. A history of cardiovascular disease and albuminuria, however, increased the risk of a reduction of life expectancy. These results show that, in a shared care environment, a normal life expectancy is achievable in type 2 diabetes patients.

Skin color independent assessment of aging using skin autofluorescence

Skin autofluorescence (AF) for the non-invasive assessment of the amount of accumulated tissue Advanced Glycation Endproducts (AGEs) increases with aging. In subjects with darker skin colors, measurements typically result in lower AF values than in subjects with fair skin colors, e.g. due to selective absorption by skin compounds. Our aim was to provide a new method for calculating skin AF, yielding values that are independent of skin color. The deviation of skin AF of healthy subjects with various darker skin types (N = 99) compared to reference values from Caucasians showed to be a function of various parameters that were derived from reflectance and emission spectra in the UV and visible range (adjusted R(2) = 80%). Validation of the new algorithm, based on these findings, in a separate dataset (N = 141) showed that results of skin AF can now be obtained to assess skin AGEs independently of skin color.

Skin Autofluorescence as a Measure of Advanced Glycation End Products Deposition Is Elevated in Peripheral Artery Disease

Objective—Evidence for an important role of advanced glycation end products (AGEs) in the development of atherosclerosis and cardiovascular disease beyond diabetes mellitus and renal disease is growing. Skin autofluorescence (SAF) is a validated noninvasive measure of tissue AGEs. We hypothesized that SAF is elevated in peripheral artery disease (PAD). Methods and Results—A case–control study was performed in 492 patients with PAD and 164 controls, matched for age (mean 66±10 years) and presence of diabetes mellitus. Cardiovascular risk factors and comorbidity (coronary artery disease, cerebrovascular disease, abdominal aortic aneurysm) were assessed. SAF was measured with the AGE Reader. SAF was higher in patients compared with controls: geometric mean 2.77 (95% confidence interval [CI], 2.71–2.83) versus 2.44 (95% CI, 2.35–2.53) arbitrary units, P=0.4×10−8. In logistic regression, the adjusted odds ratio for the presence of PAD was 2.47 (95% CI, 1.66–3.69) per 1 unit increase of SAF. PAD patients with cardiovascular comorbidity had a higher SAF compared with those without: geometric mean 2.93 (95% CI, 2.85–3.02) versus 2.63 (95% CI, 2.55–2.71) arbitrary units, P=0.4×10−6, also after correction for confounders. Regression analysis showed that age, smoking, diabetes mellitus, chronic kidney disease, and a history of cerebrovascular disease or abdominal aortic aneurysm were independently associated with SAF in the patients with PAD. Conclusion—Accumulation of tissue AGEs is increased in patients with PAD, independent of cardiovascular risk factors and comorbidity, although these conditions are associated with a further increase. These findings underscore the importance of AGEs in PAD, irrespective of the presence of diabetes mellitus and renal insufficiency.

Microdialysis measurement of glucose in subcutaneous adipose tissue up to three weeks in Type 1 diabetic patients

BACKGROUNDnMicrodialysis of subcutaneous adipose tissue may provide an opportunity to monitor glucose continuously, when the device is connected to an extracorporal glucose sensor. We assessed whether our microdialysis probes are capable of measuring adipose tissue glucose over a prolonged period in Type 1 diabetic patients. Furthermore, the relationship between abdominal skinfold thickness and glucose recovery and the effect of spontaneous glucose excursions on its recovery were evaluated.nnnMETHODSnMicrodialysis probes were pairwise inserted subcutaneously into the abdominal fat and remained in situ for 3 weeks in eight Type 1 diabetic patients. At days 1, 3, 4, 8, 11, 16, and 18 of probe retention, glucose, as measured by microdialysis, was compared to capillary blood glucose concentrations during a 4 h period. The recovery of glucose obtained by microdialysis was expressed as a percentage of the capillary blood glucose concentration.nnnRESULTSnEleven of the 16 inserted probes (69%) were evaluable during the complete study. Recovery of glucose was lower at day 1 and 3 (51+/-23% and 56+/-18%, respectively, mean+/-S.D.) compared to values found afterwards (67+/-19%, 72+/-13%, 76+/-14%, 71+/-16%, and 76+/-18%, for day 4, 8, 11, 16, and 18, respectively, for all P<0.05 vs. day 1 and 3). Skinfold thickness was inversely related to the overall 3 week glucose recovery (r=-0.76; P<0.03). Recovery was similar over a wide range of capillary blood glucose concentrations.nnnCONCLUSIONSnProlonged in vivo retention of microdialysis probes improves the recovery and lowers the variability of adipose tissue-sampled glucose in Type 1 diabetic patients. These findings show that microdialysis-based glucose measurements offer an opportunity for prolonged glucose monitoring.

Skin autofluorescence is increased in patients with carotid artery stenosis and peripheral artery disease

Advanced glycation end products (AGEs) have a pivotal role in atherosclerosis. We evaluated skin autofluorescence (SAF), a non-invasive measurement of tissue AGE accumulation, in patients with carotid artery stenosis with and without coexisting peripheral artery occlusive disease (PAOD). SAF was measured using the AGE Reader™ in 56 patients with carotid artery stenosis and in 56 age- and sex-matched healthy controls without diabetes, renal dysfunction or known atherosclerotic disease. SAF was higher in patients with carotid artery stenosis compared to the control group: mean 2.81 versus 2.46 (Pxa0=xa00.002), but especially in the younger age group of 50–60xa0years old: mean 2.82 versus 1.94 (Pxa0=xa00.000). Patients with carotid artery stenosis and PAOD proved to have an even higher SAF than patients with carotid artery stenosis only: mean 3.28 versus 2.66 (Pxa0=xa00.003). Backward linear regression analysis showed that age, smoking, diabetes mellitus, renal function and the presence of PAOD were the determinants of SAF, but carotid artery stenosis was not. SAF is increased in patients with carotid artery stenosis and PAOD. The univariate and multivariate associations of SAF with age, smoking, diabetes, renal insufficiency and PAOD suggest that increased SAF can be seen as an indicator of widespread atherosclerosis.

Carotid artery intima media thickness associates with skin autofluoresence in non-diabetic subjects without clinically manifest cardiovascular disease

Eur J Clin Invest 2010; 40 (9): 812–817

Lifestyle and clinical determinants of skin autofluorescence in a population-based cohort study

Skin autofluorescence (SAF) is a noninvasive marker of advanced glycation end products (AGEs). In diabetes, higher SAF levels have been positively associated with long‐term complications, cardiovascular morbidity and mortality. Because little is known about the factors that influence SAF in nondiabetic individuals, we assessed the association of clinical and lifestyle parameters with SAF as well as their interactions in a large‐scale, nondiabetic population and performed the same analysis in a type 2 diabetic subgroup.