AimThe United Kingdom Prospective Diabetes Study (UKPDS) study showed that glycaemic control (HbA(1c)) can predict vascular complications in Type 2 diabetes mellitus. The Diabetes Control and Complications Trial (DCCT) study showed that accumulation of advanced glycation end products (AGEs) from skin biopsies predicts vascular complications in Type 1 diabetes. Previously, we showed that tissue AGEs can be measured non-invasively using skin autofluorescence (SAF). The aim of this study was to compare the predictive value of HbA(1c) and SAF for new macrovascular events and microvascular complications in people with Type2 diabetes. MethodsA prospective cohort study of 563 participants, median age 64years [interquartile range (IQR) 57-72], diabetes duration of 13years, from five Dutch hospitals was performed. ResultsAfter a median follow-up of 5.1 (IQR 4.3-5.9)years, 79 (15%) participants had died and 49 (9%) were lost to follow-up. Some 133 (26%) developed a microvascular complication and 189 (37%) a macrovascular event. Tertiles of HbA(1c) were significantly associated with development of microvascular complications (log rank P=0.022), but not with macrovascular events. Tertiles of SAF were significantly associated with macrovascular events (log rank P=0.003). Cox regression analysis showed SAF was associated with macrovascular events: crude hazard ratio (HR) 1.53 (P<0.001) per unit increase, HR 1.28 (P=0.03) after correction for UKPDS score. HbA(1c) was predictive for microvascular complications: crude HR 1.20 (P=0.004), HR 1.20 (P=0.004) after correction for UKPDS score. ConclusionThis study shows that tissue accumulation of AGEs, assessed by SAF, is associated with development of macrovascular events in people with Type2 diabetes, whereas HbA(1c) is associated with the development of microvascular complications.

Autofluorescentie van de huid is een niet-invasieve maat voor de stapeling van zogeheten advanced glycation endproducts (AGE’s) die ontstaan door glycemische en oxidatieve stress. In een eerder onderzoek bij patiënten met type 2 diabetes mellitus afkomstig uit de huisartsenpraktijk bleek de mate van autofluorescentie van de huid gecorreleerd te zijn aan de aanwezigheid van micro- en macrovasculaire complicaties.

Diabet. Med. 29, 1556–1561 (2012)AbstractAims Skin autofluorescence is a non‐invasive marker of advanced glycation end product accumulation. In a previous study, skin autofluorescence correlated with and predicted micro‐ and macrovascular complications in Type 2 diabetes in a primary care setting. The present cross‐sectional study aims to confirm the association between skin autofluorescence and diabetic complications in patients with Type 2 diabetes in a multi‐centre secondary care setting.Methods We analysed 563 subjects with Type 2 diabetes mellitus from five Dutch hospitals.Results Median age was 64 years, median duration of diabetes 13 years and median HbA1c 58 mmol/mol (7.5%). Sixty‐one per cent of patients had microvascular complications (38% nephropathy, 36% retinopathy, 35% neuropathy) and 42% had macrovascular complications. Median UK Prospective Diabetes Study 10‐year risk for coronary events was 19%. Median skin autofluorescence was elevated compared with age‐matched healthy control subjects: 2.77 (interquartile range 2.39–3.28) vs. 2.46 (2.08–2.84) arbitrary units. Skin autofluorescence was particularly increased in patients with complications: no complications, median 2.56 (2.26–2.90); microvascular complications, 2.79 (2.38–3.29); macrovascular complications, 2.85 (2.41–3.41); both micro‐ and macrovascular complications, 2.96 (2.56–3.60) arbitrary units, P < 0.001. Logistic regression analysis showed that age, duration of diabetes, renal function, gender, atrial fibrillation and skin autofluorescence were independently associated with macrovascular complications. Multiple regression analysis identified age, smoking, renal function, macrovascular complications and the number of microvascular complications as the determinants of skin autofluorescence.Conclusions This study confirms that skin autofluorescence is increased in patients with Type 2 diabetes in a secondary care setting. Skin autofluorescence was associated with macrovascular complications in patients with diabetes and this association was independent of classical risk factors.

Background Capillary leakage of sodium-fluorescein (NaF) in the skin reflects capillary permeability and may be a marker of diabetes-associated microcirculatory abnormalities.Design We evaluated transcapillary skin NaF leakage by fluorescence videodensitometry in 10 normoalbuminuric, 10 microalbuminuric Type I diabetic men (diabetes duration > 10 years) and 10 healthy subjects. The microalbuminuric patients were restudied after 6 weeks treatment with the ACE-inhibitor enalapril, 10 mg once daily. All measurements were performed at a blood glucose level of 5 mmolL(-1) .Results Transcapillary NaF leakage was strongly increased in normoalbuminuric Type 1 diabetic patients compared to healthy subjects (P < 0.001) and was still further increased in microalbuminuric Type 1 diabetic patients (P < 0.01 compared to normoalbuminuric patients). Enalapril reduced NaF leakage (p < 0.05), mean arterial blood pressure (P < 0.05) and microalbuminuria (P < 0.05). After treatment, NaF leakage was not different from that in normoalbuminuric patients.Conclusions Capillary permeability, as determined by NaF leakage, is elevated in normoalbuminuric Type 1 diabetic patients with long-standing disease, and the excess elevation in microalbuminuric Type 1 diabetic patients is ameliorated by ACE-inhibition. Skin NaF videodensitometry seems a useful tool to document capillary permeability in intervention studies.

We assessed the day-to-day reproducible of vitreous fluorophotometry in 7 type 1 diabetic patients and in 1 healthy control subject. The coefficient of variation for duplicate measurements was 33.7, 40.3 and 23.6%, for the right eyes, the left eyes and mean values of both eyes, respectively. Assessment of reproducibility in 1 healthy subject, measured 4 times, resulted in coefficients of variation of about 60%. These values are somewhat worse than those obtained by others in healthy subjects. Since technical problems do not seem to play a significant role in this regard, our reproducibility results reflect the true biological variability of the permeability of the blood-retina barrier assessed by vitreous fluorophotometry in diabetic patients. This variability is substantial. Therefore, we conclude that this method is not precise enough to be used in intervention studies with a limited number of subjects.

In a healthy reference population, hemoglobin (Hgb) and hematocrit (Hct) have been proposed as surrogate markers for whole blood water (WBW). We have extended this study under different physiological and pathological conditions in two longitudinal series, viz. (1) acute hyper- and hypohydration experiments in a healthy individual and (2) three athletes running 5 km each, and in three transverse series, viz. (3) a young reference population (n = 97, 49 females), (4) an old reference population (n = 37, nine females) consisting of inhabitants of a nursing home and (5) cardiac, hematological and renal patients including severe anaemia, polycythaemia and abnormal protein levels (n = 50, 25 females) with suspected hydration disturbances. The only sex difference found was a lower WBW in males in the young reference group. The percentage change of PW was less than that of WBW. In all five groups together (n = 293) WBW correlated closely (P < 0.0001) with Hgb and Hct (both r = -0.95) and with erythrocyte count (r = -0.85), whereas PW correlated with total protein (Tprot) (r = -0.84). In the longitudinally studied groups (1) and (2) WBW also correlated (P < 0.0001) with cholesterol, Ca, Tprot, albumin, platelets, globulin and white blood cells (r +/- 0.98-0.37), while PW correlated (P < 0.0001) not only with the same clinicochemical parameters but also with Hct, Hgb and red blood cells (r +/- 0.98-0.44). The homeostasis of PW is more narrowly regulated than that of WBW. Hgb, Hct and erythrocyte count reflect WBW and Tprot reflects PW also under disease conditions. WBW (mass%) can be calculated from Hgb and Hct using the formulae: -0.09 x Hgb (g/l) + 91.7 and -28.6 x Hct (v/v) + 91.8 and PW (mass%) from Tprot using the formula: -0.09 x Tprot (g/l) + 97.6. Other correlations were observed only in a longitudinal setting and presumably are due to concentration and dilution.

The transcapillary and interstitial diffusion of intravenously administered sodium fluorescein is used as a marker for capillary permeability. Fluorescein diffusion has been expressed by different parameters with reported coefficients of variation of 14-20%. Aim of the present study is to select a parameter which combines excellent reproducibility with the potential for discriminating insulin-dependent diabetic patients from healthy subjects. We performed three experiments to assess day-to-day reproducibility: 5 healthy subjects were measured twice, 1 healthy subject was measured 6 times and 1 subject with insulin-dependent diabetes mellitus was measured 5 times. We averaged the relative fluorescence light intensity (IREL(t)] from dye arrival until a certain time point [IAV(t)], instead of using the relative intensity at one time point. IAV (7 min) showed markedly improved reproducibility, expressed as geometric mean of the coefficients of variation of the three separate experiments: 10%. In addition, a group of 12 insulin-dependent diabetic subjects was compared with 12 healthy control subjects. Median IAV (7 min) was 69.5% (95% CI: 65.3-78.1%) in the diabetic subjects and 54.9% (95% CI: 52.1-60.0%) in the control subjects (p < 0.001). Since IAV (7 min) combines excellent reproducibility with a good discriminating power, we advise its use in further studies.

We have assessed gravimetric methods for determination of intravascular water, established whole blood-, plasma- and erythrocyte water reference values in a healthy volunteer group (n = 97, 48 females) and correlated these variables with 30 simultaneous hematological, clinicochemical and body parameters. The water standard was 55.56 mol/kg = 100 mass%. For erythrocyte water determination three methods were evaluated: 2 indirect methods were easy to perform, the third, using a hematocrit centrifuge, was the most reliable. Imprecision (within-batch coefficient of variation (CV), %) was excellent: whole blood 0.2, plasma 0. 1, erythrocytes 0.7-2.2 and recoveries (means, %) 99.7- 100. 1. Serum water was found to be slightly higher than plasma water. Volunteer group, mean reference values, mass%: whole blood water 79.7, plasma water 91.2, erythrocyte water, three methods 66.2, 64.6 and 64.2, respectively. Females had mean 1.6 mass% higher whole blood water and 0.9-1.0 mass% higher erythrocyte water than males with no difference in plasma water. In the volunteer group whole blood water correlated strongly with hematocrit (r = -0.96), hemoglobin (r = -0.94) and erythrocytes (r = -0.85) and centrifuge hematocrit (r = -0.91). Plasma water correlated strongly with plasma total protein (r = -0.74, all correlations P < 0.001). Hemoglobin and hematocrit can serve as surrogate parameters for whole blood water when water determination is not available; total protein reflects plasma water.