Skin autofluorescence in diabetes mellitus

AGEs ofwel advanced glycation endproducts zijn onomkeerbaar versuikerde stoffen, die voornamelijk aan eiwitten zijn gekoppeld, en die bij ieder mens stapelen. Bij iemand met diabetes mellitus gaat dit proces echter versneld. AGEs hebben een belangrijke rol bij het ontstaan van chronische complicaties van diabetes en atherosclerose. Tot recent werden weefsel-AGEs via huidbiopten gemeten. Dat is een belastende methode, ongeschikt voor toepassing op grote schaal, of voor herhaalde metingen. Het is vanuit de literatuur bekend dat sommige AGEs fluoresceren. Enkele jaren geleden is de Autofluorescence reader ontwikkeld, dat gebruikmakend van fluorescentieprincipes, niet-invasief autofluorescentie van de huid meet en een maat is voor weefsel-AGEs. Bij type 1, type 2 diabetes patiënten, met en zonder complicaties, werden autofluorescentie metingen gedaan met een monochromator, resulterend in excitatie-emissie maps. Hierbij wordt de huid met licht van een specifieke golflengte beschenen, om verschillende fluorophoren te identificeren. Hieruit bleek dat er geen verschil was in fluorescentiekarakteristieken tussen de onderzochte patiëntgroepen. In 2001 werd in een type 2 diabetes cohort (+/-1000) uit de regio Zwolle, huid autofluorescentie gemeten. Autofluorescentie bleek gerelateerd aan leeftijd, roken, HbA1c en aan microvasculaire en macrovasculaire complicaties. Na een follow-up van 3.5 jaar werden eindpunten verzameld als cardiovasculaire events en mortaliteit. Autofluorescentie blijkt een betere voorspeller t.a.v. mortaliteit en cardiovasculaire events dan HbA1c. Verder is meting van autofluorescentie van aanvullende waarde aan de UKPDS Risk score. Tot slot bleek na een follow-up van 5 jaar de levensverwachting van deze goed gereguleerde type 2 diabetes populatie niet anders dan die van de gemiddelde Nederlander.

Pitfalls in blood pressure measurement in daily practice

Background. Accurate blood pressure (BP) readings and correctly interpreting the obtained values are of great importance. However, there is considerable variation in the different BP measuring methods suggested in guidelines and used in hypertension trials. Objective. To compare the different methods used to measure BP; measuring once, the method used for a large study such as the UKPDS, and the methods recommended by various BP guidelines. Methods. In 223 patients with type 2 diabetes from five family practices BP was measured according to a protocol to obtain the following data: A = first reading, B = mean of two initial readings, C = at least four readings and the mean of the last three readings with less than 15% coefficient of variation difference, D = mean of the first two consecutive readings with a maximum of 5 mm Hg difference. Mean outcomes measure is the mean difference between different BP measuring methods in mm Hg. Results. Significant differences in systolic/diastolic BP were found between A and B [mean difference (MD) systolic BP 1.6 mm Hg, P < 0.001], B and C (MD 5.7/2.8 mm Hg, P < 0.001), B and D (MD 6.2/2.8 mm Hg, P < 0.001), A and C (MD 7.3/3.3 mm Hg), and A and D (MD 7.9/3.0 mm Hg, P < 0.001). Conclusion. Different methods to assess BP during one visit in the same patient lead to significantly different BP readings and can lead to overestimation of the mean BP. These differences are clinically relevant and show a gap between different methods in trials, guidelines and daily practice

Skin autofluorescence - A tool to identify type 2 diabetic patients at risk for developing microvascular complications

Abstract: OBJECTIVE - Skin auto fluorescence 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 assesse at baseline and at the end of follow-up. Single end points were the development of diabetes-sassociated 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 auto fluorescence as a predictor for development of any microvascular complication along with AlC, for development of neuropathy along with smoking, and for development of (micro)albuminuria together with sex, AlC, 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.

The association between various smoking behaviors, cotinine biomarkers and skin autofluorescence, a marker for advanced glycation end product accumulation.

Background: Skin autofluorescence, a biomarker for advanced glycation end products (AGEs) accumulation, has been shown to predict diabetes-related cardiovascular complications and is associated with several environmental and lifestyle factors. In the present study, we examined the association between various smoking behaviors and skin autofluorescence, as well as the association between several cotinine biomarkers and skin autofluorescence, using both epidemiological and metabolomics data. Methods: In a cross-sectional study, we evaluated participants from the LifeLines Cohort Study and the Qatar Metabolomics Study on Diabetes (QMDiab). In the LifeLines Cohort Study smoking behavior and secondhand smoking were assessed in 8,905 individuals including 309 individuals (3.5%) with type 2 diabetes. In QMDiab, cotinine biomarkers were measured in saliva, plasma and urine in 364 individuals of whom 188 (51%) had type 2 diabetes. Skin autofluorescence was measured non-invasively in all participants using the AGE Reader. Results: Skin autofluorescence levels increased with a higher number of hours being exposed to secondhand smoking. Skin autofluorescence levels of former smokers approached levels of never smokers after around 15 years of smoking cessation. Urinary cotinine N-oxide, a biomarker of nicotine exposure, was found to be positively associated with skin autofluorescence in the QMDiab study (p = 0.03). Conclusions: In the present study, we have demonstrated that secondhand smoking is associated with higher skin autofluorescence levels whereas smoking cessation has a beneficial effect on skin autofluorescence. Finally, urinary cotinine N-oxide might be used as an alternative way for questionnaires to examine the effect of (environmental) tobacco smoking on skin autofluorescence

Skin autofluorescence is related to tobacco smoke and nicotine exposure.

Clinical epidemiolog