GDF15 reflects beta cell function in obese patients independently of the grade of impairment of glucose metabolism.

BACKGROUND AND AIMS: Growth differentiation factor 15 (GDF15) is a strong predictor of cardiovascular morbidity and mortality found to be both marker and target of impaired glucose metabolism. GDF15 increases following glucose administration and is up-regulated in obesity and diabetes. We investigate here the relationship between GDF15 and beta cell function. METHODS AND RESULTS: In this cross-sectional study we evaluated GDF15 concentrations in 160 obese subjects (BMI 35-63 kg/m2, age 39.4 ± 18.6 years, m/f 38/122) who underwent a 75 g oral glucose tolerance test (OGTT). Based on the OGTT results, the cohort was divided into two groups: 1) normal fasting glucose and normal glucose tolerance (n = 80), 2) impaired fasting glucose, impaired glucose tolerance or type 2 diabetes (n = 80). The relationship of GDF15 to fasting and OGTT-based dynamic insulin sensitivity and insulin secretion parameters was evaluated. GDF15 was higher in the prediabetes and diabetes groups and correlated with HbA1c, glucose, insulin as well as baseline and dynamic indices of insulin sensitivity and estimated beta cell function. Multiple regression analysis revealed that age, waist-to-height ratio, glomerular filtration rate and prehepatic beta cell function, but not the grade of impairment of glucose metabolism, were independent predictors of GDF15. Subgroup analysis showed that of all parameters of glucose metabolism only C-peptide, fasting prehepatic beta cell function and insulinogenic index remained significantly related to GDF15 in both groups. CONCLUSION: We conclude that in patients with severe obesity, GDF15 strongly relates to beta cell function and should be further investigated as a potential therapeutic target and biomarker guiding treatment options.

Insulin resistance and ß-cell function in smokers: results from the EGIR-RISC European multicentre study.

AIMS: Tobacco smoking is known to increase the long-term risk of developing Type 2 diabetes mellitus, but the mechanisms involved are poorly understood. This observational, cross-sectional study aims to compare measures of insulin sensitivity and ß-cell function in current, ex- and never-smokers. METHODS: The study population included 1246 people without diabetes (mean age 44 years, 55% women) from the EGIR-RISC population, a large European multicentre cohort. Insulin sensitivity was measured using a hyperinsulinaemic, euglycaemic clamp and the homeostatic model assessment - insulin resistance (HOMA-IR) index. Two ß-cell function parameters were derived from measures during an oral glucose tolerance test: the early insulin response index and ß-cell glucose sensitivity. Additionally, the areas under the curve during the oral glucose tolerance test were calculated for glucose, insulin and C-peptide. RESULTS: According to smoking habits, there were differences in insulin sensitivity, which was lower in women who smoked, and in ß-cell glucose sensitivity, which was lower in men who smoked, but these associations lost significance after adjustment. However, after adjustment, the areas under the glucose and the C-peptide curves during the oral glucose tolerance test were significantly higher in men who smoked. CONCLUSIONS: Smoking habits were not independently associated with insulin sensitivity or ß-cell function in a healthy middle-aged European population. Health-selection bias, methodological shortcomings or a true lack of causal links between smoking and impaired insulin sensitivity/secretion are possible explanations. The mechanisms behind the observed increased glucose and C-peptide areas under the curve during the oral glucose tolerance test in male smokers need to be further evaluated.

Suppression of plasma free fatty acids reduces myocardial lipid content and systolic function in type 2 diabetes.

BACKGROUND AND AIM: Type 2 diabetes (T2DM) is closely associated with the development of heart failure, which might be related with impaired substrate metabolism and accumulation of myocardial lipids (MYCL). The aim of this study was to investigate the impact of an acute pharmacological inhibition of adipose tissue lipolysis leading to reduced availability of circulating FFA on MYCL and heart function in T2DM. METHODS AND RESULTS: 8 patients with T2DM (Age: 56 ± 11; BMI: 28 ± 3.5 kg/m(2); HbA1c: 7.29 ± 0.88%) were investigated on two study days in random order. Following administration of Acipimox or Placebo MYCL and heart function were measured by (1)H-magnetic-resonance-spectroscopy and tomography at baseline, at 2 and at 6 h. Acipimox reduced circulating FFA by -69% (p < 0.001), MYCL by -39 ± 41% (p < 0.001) as well as systolic heart function (Ejection Fraction (EF): -13 ± 8%, p = 0.025; Cardiac Index: -16 ± 15%, p = 0.063 compared to baseline). Changes in plasma FFA concentrations strongly correlated with changes in MYCL (r = 0.707; p = 0.002) and EF (r = 0.651; p = 0.006). Diastolic heart function remained unchanged. CONCLUSIONS: Our results indicate, that inhibition of adipose tissue lipolysis is associated with a rapid depletion of MYCL-stores and reduced systolic heart function in T2DM. These changes were comparable to those previously found in insulin sensitive controls. MYCL thus likely serve as a readily available energy source to cope with short-time changes in FFA availability.

Fasting and postprandial liver glycogen content in patients with type 1 diabetes mellitus after successful pancreas-kidney transplantation with systemic venous insulin delivery.

BACKGROUND: In patients with type 1 diabetes mellitus (T1DM), insulin is usually replaced systemically (subcutaneously) and not via the physiological portal route. According to previous studies, the liver's capacity to store glycogen is reduced in T1DM patients, but it remains unclear whether this is due to hyperglycaemia, or whether the route of insulin supply could contribute to this phenomenon. T1DM patients after successful pancreas-kidney transplantation with systemic venous drainage (T1DM-PKT) represent a suitable human model to further investigate this question, because they are normoglycaemic, but their liver receives insulin from the pancreas transplant via the systemic route. MATERIALS AND METHODS: In nine T1DM-PKT, nine controls without diabetes (CON) and seven patients with T1DM (T1DM), liver glycogen content was measured at fasting and after two standardized meals employing (13) C-nuclear-magnetic-resonance-spectroscopy. Circulating glucose and glucoregulatory hormones were measured repeatedly throughout the study day. RESULTS: The mean and fasting concentrations of peripheral plasma glucose, insulin, glucagon and C-peptide were comparable between T1DM-PKT and CON, whereas T1DM were hyperglycaemic and hyperinsulinaemic (P < 0·05 vs T1DM-PKT and CON). Total liver glycogen content at fasting and after breakfast did not differ in the three groups. After lunch, T1DM-PKT and T1DM had a 14% and 21% lower total liver glycogen content than CON (P < 0·02). CONCLUSION: In spite of normalized glycaemic control, postprandial liver glycogen content was reduced in T1DM-PKT with systemic venous drainage. Thus, not even optimized systemic insulin substitution is able to resolve the defect in postprandial liver glycogen storage seen in T1DM patients.

Effects of pioglitazone versus glimepiride exposure on hepatocellular fat content in type 2 diabetes.

AIMS: Thiazoledinediones decrease blood glucose by their insulin-sensitizing properties. Here, we examined whether pioglitazone plus nateglinide (PIO) interferes with hepatocellular lipid (HCL) content and/or improves insulin sensitivity in well-controlled non-obese patients with type 2 diabetes mellitus (T2DM). METHODS: Sixteen patients [body mass index (BMI): 28 ± 1 kg/m(2) ; HbA1c: 7.1 ± 0.6%] were studied in a randomized, double-blind, 12-week parallel group trial, whereas matched healthy humans [non-diabetic control subjects (CON), BMI: 26 ± 1 kg/m(2)] were studied once. Treatment with pioglitazone (30 mg/day) plus nateglinide (PIO arm) to control for glimepiride-induced insulin secretion was compared to treatment with glimepiride (2 mg/day) plus placebo (GLI arm). Multinuclei magnetic resonance spectroscopy (MRS) was combined with pancreatic normoglycaemic-two-step-insulin clamps and stable isotopes to assess glucose turnover, glucose transport/phosphorylation, HCL and intramyocellular lipid (IMCL) contents, non-esterified fatty acids (NEFA) and adipokines. RESULTS: At baseline, HCL was approximately 5.6-fold higher in T2DM (p < 0.05 vs. CON). This was paralleled by approximately doubled leptin : adiponectin ratios (p < 0.05). HCL decreased by approximately 39% (p < 0.05) after PIO and only tended to decrease after GLI (p = 0.12). Treatment with PIO did not affect leptin : adiponectin ratios, but slightly improved (p < 0.05) insulin-mediated NEFA suppression, which related to lower HCL. PIO further prevented the insulin-induced increase in IMCL content of soleus and tibialis anterior muscles. Peripheral and hepatic insulin sensitivity, glucose transport and glycaemic control did not change in both groups. CONCLUSION: Short-term, low-dose thiazolidendione treatment improves insulin sensitivity of lipolysis and HCL, without affecting muscle and liver insulin sensitivity. It appears that metabolic PIO action in T2DM is primarily mediated via a decline in HCL associated with greater sensitivity of lipolysis to insulin.

Taking small steps towards targets - perspectives for clinical practice in diabetes, cardiometabolic disorders and beyond.

Big changes are hard. When trying to achieve guideline targets in diabetes and cardiometabolic disorders, patients can lack commitment or suffer despondency. It is much easier to make small changes in lifestyle or treatment, which are less noticeable and easier to manage long-term. Obesity is central to the cardiometabolic disorders, and even small weight losses of 2-5% can improve the cardiometabolic risk profile and substantially reduce the risk of developing type 2 diabetes. Likewise, small increases in physical activity, such as 15-30 min of brisk walking per day, can cut the risk of heart disease by 10%. Lifestyle or treatment changes that lead to small improvements in metabolic parameters also impact patient outcome - for example, a 5 mmHg decrease in blood pressure can translate into significant reductions in the rates of myocardial infarction and cardiovascular mortality. Benefits of small changes can also be seen in health economic outcome models. Implementing change at an individual versus a population level has different implications for overall benefit and patient motivation. Even very small steps taken in trying to reach guideline targets should represent a positive achievement for patients. Patient engagement is essential - only when patients commit themselves to change can benefits be maintained, and physicians should recognise their influence. Small changes in individual parameters can result in significant beneficial effects; however, a major impact can occur when small changes are made together in multiple parameters. More research is required to elucidate the full impact of small changes on patient outcome.

Moderate alcohol consumption is associated with improved insulin sensitivity, reduced basal insulin secretion rate and lower fasting glucagon concentration in healthy women.

AIMS/HYPOTHESIS: Moderate alcohol consumption is associated with a reduced risk of type 2 diabetes with a stronger effect in women. As the underlying mechanisms remain poorly characterised, we investigated its relationship with insulin resistance, insulin secretion, clearance of insulin and glucagon concentration. METHODS: One-thousand two-hundred and seventy-six non-diabetic individuals from the RISC (relationship between insulin sensitivity and cardiovascular disease) study without high alcohol consumption were studied; all had a euglycaemic-hyperinsulinaemic clamp and an OGTT with assessment of insulin sensitivity, secretion and clearance. RESULTS: Alcohol consumption was positively associated with insulin sensitivity in women (ß = 0.15, p ( trend ) = 0.005) and in men (ß = 0.07, p ( trend ) = 0.07) after controlling for age, centre, waist, smoking and physical activity. In women, this association persisted after adjustment for adiponectin but was attenuated after controlling for HDL-cholesterol, suggesting that part of the protection is related to a higher HDL-cholesterol concentration. Higher alcohol consumption was associated with lower basal insulin secretion in women only (ß = -0.10, p ( trend ) = 0.004) and this association persisted after adjustment for insulin sensitivity. In men, increasing alcohol consumption was associated with enhanced insulin clearance and increased fasting NEFA concentrations, independently of insulin sensitivity. Fasting glucagon decreased with increasing alcohol in women only (abstainers 9.2 ± 4.4; <28 g/week 8.6 ± 4.0; 28-64 g/week 8.1 ± 3.7; >64 g/week 7.5 ± 3.1 pmol/l; p ( trend ) = 0.01). CONCLUSIONS/INTERPRETATION: Light-to-moderate alcohol consumption was associated in healthy women with enhanced insulin sensitivity, reduced basal insulin secretion rate and lower fasting plasma glucagon concentration, providing consistent mechanisms for the reduced risk of diabetes.

Insulin resistance is not associated with myocardial steatosis in women.

AIMS/HYPOTHESIS: Insulin resistance, an independent risk-factor for cardiovascular disease, precedes type 2 diabetes and is associated with ectopic lipid accumulation in skeletal muscle and liver. Recent evidence indicates that cardiac steatosis plays a central role in the development of diabetic cardiomyopathy. However, it is not known whether insulin resistance as such in the absence of type 2 diabetes is associated with heart steatosis and/or impaired function. We therefore assessed myocardial steatosis and myocardial function in a sample of women with normal insulin sensitivity, insulin resistance, impaired glucose tolerance (IGT) and type 2 diabetes. METHODS: Magnetic resonance imaging and localised spectroscopy were used to measure left ventricular dynamic variables and myocardial lipid accumulation in interventricular septum of non-diabetic, age- and BMI-matched insulin-sensitive (n = 11, 47 ± 6 years, BMI 25 ± 2 kg/m(2); clamp-like index [CLIX] = 9.7 ± 0.7) and insulin-resistant (n = 10, 48 ± 5 years, 27 ± 4 kg/m(2); CLIX = 4.5 ± 0.4) women with normal glucose tolerance as well as of women with IGT (n = 6, 45 ± 5 years, 28 ± 6 kg/m(2); CLIX = 3.6 ± 1.1) and type 2 diabetes (n = 7, 52 ± 10 years, 27 ± 3 kg/m(2)). RESULTS: Myocardial lipid content was increased in type 2 diabetic women only (insulin-sensitive 0.4 ± 0.2% [means ± SD]; insulin-resistant 0.4 ± 0.1%; IGT 0.5 ± 0.2%; type 2 diabetes 0.7 ± 0.3%; p < 0.05). In insulin-resistant and type 2 diabetic women, stroke volume was lower (-15% and -27%, respectively, vs insulin-sensitive) and heart rate was higher (11% and 14%, respectively, vs insulin-sensitive, p < 0.05). No other differences in systolic and diastolic function were observed between study groups. CONCLUSIONS/INTERPRETATION: In contrast to liver and skeletal muscle, insulin resistance as such is not associated with increased myocardial lipid accumulation.

Persistent arterial stiffness and endothelial dysfunction following successful pancreas-kidney transplantation in Type 1 diabetes.

OBJECTIVE: Successful simultaneous pancreas-kidney transplantation (SPK) in Type 1 diabetic (T1DM) patients results in improved cardiovascular outcome and survival. However, it is doubtful whether the impairment of cardiovascular and endothelial function in T1DM can be completely reversed. METHODS: Pulse-wave velocity, stroke volume, heart rate, serological markers of endothelial dysfunction (soluble intercellular, vascular cell-adhesion molecules, E-selectin, and plasminogen-activator-inhibitor-1) were measured in 10 T1DM patients after SPK with non-diabetic glucose levels, 10 T1DM patients with poor [T1DM>8; glycated haemoglobin (HbA1c)>8%], and 10 with good glucose control (T1DM<7, HbA1c<7%), in 6 non-diabetic patients after kidney transplantation (KT) and 9 non-diabetic control subjects (CON), matching for major anthropometric characteristics. RESULTS: Pulse-wave velocity was increased in SPK (P < 0.02 vs. CON, KT, T1DM<7) and in T1DM>8 (P < 0.02 vs. T1DM<7). Systolic blood pressure was increased in SPK (P < 0.05 vs. CON). Stroke volume was reduced in SPK, T1DM>8 and T1DM<7 and KT (P < 0.01 vs. CON). Heart rate was elevated in SPK and in T1DM>8 (P < 0.0003 vs. CON and T1DM<7). In SPK, soluble intercellular and vascular cell-adhesion molecules were 100% and 44% higher (P < 0.03 vs. CON), respectively, while plasminogen-activator-inhibitor-1 was decreased in SPK (P < 0.02 vs. CON). CONCLUSION: T1DM patients after SPK experience arterial stiffness, a higher heart-rate and blood pressure, reduced stroke volume and serological signs of endothelial dysfunction. Thus, functional and structural cardiovascular alterations as a result of glucotoxicity, uraemia and hypertension in T1DM might not be completely resolved by SPK.

Beta cell (dys)function in non-diabetic offspring of diabetic patients.

AIMS/HYPOTHESIS: The first-degree offspring of patients with type 2 diabetes are prone to develop type 2 diabetes, and have both insulin resistance and beta cell impairment. However, it is still unclear whether both pathophysiological features are inseparably combined and which is the outstanding determinant in the offspring. METHODS: Glucose metabolism, insulin sensitivity (calculated as M value divided by insulin [M/I]) and beta cell function were studied in the offspring of individuals with type 2 diabetes (n = 187; 57% females; age 43.8 +/- 8.1 years; BMI 26.8 +/- 4.5 kg/m(2)) and in individuals without a family history of type 2 diabetes (controls, n = 519, 55% females; age 43.4 +/- 8.2 years; BMI 26.4 +/- 3.7 kg/m(2), no significant differences between the groups for any characteristic) by performance of 75 g OGTT and 2 h hyperinsulinaemic (40 mU min(-1) m(-2))-isoglycaemic clamp tests. Beta cell function was evaluated by calculating insulinogenic index (IGI) from C-peptide AUC:glucose AUC ratios from the first hour of OGTT (IGI[60 min]) and from the total OGTT (IGI[120 min]). RESULTS: During the OGTT, the offspring of individuals with type 2 diabetes showed 4-14% higher plasma glucose from 30 to 120 min (p < 0.05) and 20-29% higher serum insulin from 90 to 120 min, but decreased IGI(60 min) and IGI(120 min) (p < 0.05). M/I was 11% lower in the offspring of affected individuals than in controls (p < 0.01). To study the offspring of patients with type 2 diabetes with insulin sensitivity similar to that of the control group, the offspring of affected patients were divided into M/I quartiles. Those in the third M/I quartile showed M/I values and major anthropometric characteristics similar to those of the controls, but insulin AUC and C-peptide AUC values were lower in the first hour and the total OGTT (p < 0.05). The third M/I quartile had lower IGI values at 60 min and 120 min: 11% and 14% lower, respectively (p < 0.02). CONCLUSIONS/INTERPRETATION: The first-degree offspring of type 2 diabetic patients show insulin resistance and beta cell dysfunction in response to oral glucose challenge. Beta cell impairment exists in insulin-sensitive offspring of patients with type 2 diabetes, suggesting beta cell dysfunction to be a major defect determining diabetes development in diabetic offspring.

Glucose turnover and intima media thickness of internal carotid artery in type 2 diabetes offspring.

BACKGROUND: First-degree offspring (OFF) of type 2 diabetic (T2DM) patients bear a approximately 40% lifetime risk of developing T2DM. They are insulin resistant and carry a risk of premature atherosclerosis, the extent of which can be estimated by intima media thickness (IMT) of the carotid artery (CA). Thus, this study examines parameters of glucose and lipid metabolism, insulin sensitivity, beta cell function (BCF) and IMT with their interrelationships in middle-aged OFF. MATERIALS AND METHODS: T2DM-OFF (n = 18, 14f/4m, 45.6 +/- 2.1 years, BMI: 26 +/- 1 kg m(-2)) were compared with 18 matching humans without a family history of diabetes (CON; 14f/4m, 44.5 +/- 2.1 years, BMI: 24 +/- 1 kg m(-2); each P > 0.30), all with normal glucose tolerance as tested by three-hour (75 g) oral glucose tolerance tests (OGTT). Two-hour hyperinsulinaemic (40 mU min(-1).m(-2))isoglycaemic clamp tests were performed with simultaneous measurement of endogenous glucose (D-[6,6-(2)H(2)]glucose) production (EGP). IMT [internal (ICA), common CA, and bulb] were measured sonographically. BCF was assessed by Adaptation Index (AI). RESULTS: Before and during OGTT, both groups were similar in plasma glucose, insulin, C-peptide and free fatty acids (FFA), whereas OFF showed ~30% lower (P < 0.03) fasting plasma triglycerides before OGTT. During hyperinsulinaemic clamps, insulin sensitivity was approximately 38% lower (P < 0.03) in OFF who showed higher plasma FFA (44 +/- 9 micromol L(-1)) than CON (26 +/- 3 micromol L(-1), P < 0.05) after 90 min. EGP was similar in both groups. OFF had 38% (P < 0.007) reduced AI. ICA-IMT was approximately 18% higher in OFF (P < 0.002), but did not correlate with insulin sensitivity. CONCLUSION: The data obtained show middle-aged T2DM-OFF with normal glucose tolerance displaying reduced total insulin sensitivity and impaired beta cell function, which relates to impaired insulin-dependent suppression of plasma FFA and increased ICA-IMT.

Effects of free fatty acids on carbohydrate metabolism and insulin signalling in perfused rat liver.

BACKGROUND: Elevated circulating free fatty acids (FFAs) induce insulin resistance and play a crucial role in the development of type 2 diabetes, in which fasting hepatic glucose production (HGP) is increased. However, direct effects of FFAs on fasting HGP are still unclear because indirect endocrine and metabolic effects contribute to FFA action. Thus, we aimed to investigate acute direct effects of specific FFAs on fasting HGP, lactate uptake, and insulin signalling. MATERIALS AND METHODS: Isolated livers obtained from 20 h fasted rats were perfused with albumin-bound palmitate or oleate (200 micromol L(-1) each) or vehicle (control) for 180 min (n = 5-7/group). RESULTS: Compared to control, hepatic lactate uptake was increased by palmitate and oleate (~+40%; P < 0.05), while HGP from lactate (~3 mmol L(-1)) and liver glycogen content were similar. Tyrosine phosphorylation (pY) of insulin-receptor-substrate-(IRS)-2 and p70S6-kinase phosphorylation were not affected by FFAs. Palmitate decreased insulin-receptor-beta pY, IRS-1 pY and phosphoinositol-3-kinase expression by 46 +/- 16%, 46 +/- 11% and 20 +/- 9%, respectively (P < 0.03), while oleate reduced Akt phosphorylation by 85 +/- 7% (P < 0.006). CONCLUSIONS: Isolated liver perfusion with saturated or unsaturated FFAs reduced insulin signalling protein phosphorylation at different sites and increased lactate uptake without affecting HGP or glycogen content. These results suggest that at fasting, both saturated and unsaturated FFAs increase hepatic glucose precursor uptake and may, independently of insulin's presence, accelerate protein dephosphorylation of the insulin signalling cascade at different sites.

Activation of PPAR-delta in isolated rat skeletal muscle switches fuel preference from glucose to fatty acids.

AIMS/HYPOTHESIS: GW501516, an agonist of peroxisome proliferator-activated receptor-delta (PPAR-delta), increases lipid combustion and exerts antidiabetic action in animals, effects which are attributed mainly to direct effects on skeletal muscle. We explored such actions further in isolated rat skeletal muscle. MATERIALS AND METHODS: Specimens of rat skeletal muscle were pretreated with GW501516 (0.01-30 mumol/l) for 0.5, 4 or 24 h and rates of fuel metabolism were then measured. In addition, effects on mitochondrial function were determined in isolated rat liver mitochondria. RESULTS: At concentrations between 0.01 and 1 mumol/l, GW501516 dose-dependently increased fatty acid oxidation but reduced glucose utilisation in isolated muscle. Thus after 24 h of preincubation with 1 mumol/l GW501516, palmitate oxidation increased by +46+/-10%, and the following decreased as specified: glucose oxidation -46+/-8%, glycogen synthesis -42+/-6%, lactate release -20+/-2%, glucose transport -15+/-6% (all p<0.05). Reduction of glucose utilisation persisted independently of insulin stimulation or muscle fibre type, but depended on fatty acid availability (the effect on glucose transport in the absence of fatty acids was an increase of 30+/-9%, p<0.01), suggesting a role for the glucose-fatty acid cycle. At higher concentrations, GW501516 uncoupled oxidative phosphorylation by direct action on isolated mitochondria. CONCLUSIONS/INTERPRETATION: GW501516-induced activation of PPAR-delta reduces glucose utilisation by skeletal muscle through a switch in mitochondrial substrate preference from carbohydrate to lipid. High concentrations of GW501516 induce mitochondrial uncoupling independently of PPAR-delta.

Long-term mortality and incidence of renal dialysis and transplantation in type 1 diabetes mellitus.

AIMS: We investigated long-term mortality and requirement of renal replacement therapy (RRT) in type 1 diabetes mellitus (T1DM) to study risk factors and late complication incidence of T1DM in a prospective cohort study at Lainz Hospital, Vienna, Austria. METHODS: In 1983-1984, T1DM patients [n = 648; 47% females, 53% males; age, 30 +/- 11 yr; T1DM duration, 15 +/- 9 yr; body mass index, 24 +/- 4 kg/m(2); glycated hemoglobin (HbA1c), 7.6 +/- 1.6%] were stratified into HbA1c quartiles [1st, 5.9 +/- 0.5% (range, 4.2-6.5%); 2nd, 6.9 +/- 0.3% (6.6-7.4%); 3rd, 7.9 +/- 0.3% (7.5-8.4%); and 4th, 9.6 +/- 1.3% (8.5-14.8%)]. Twenty years later, both endpoints (death and RRT) were investigated by record linkage with national registries. RESULTS: At baseline, creatinine clearance, blood pressure, and body mass index were comparable among the HbA1c quartiles, whereas albuminuria was more frequent in the 4th quartile (+15%; P < 0.03). After the 20-yr follow-up, 13.0% of the patients had died [rate, 708 per 100,000 person-years (95% confidence interval, 557-859)], and 5.6% had received RRT [311 per 100,000 person-years (95% confidence interval, 210-412)]. Patients with the highest HbA1c values (4th quartile) had a higher mortality rate and a greater incidence of RRT (P < 0.04). In the Cox proportional hazards analysis, age, male gender, increased HbA1c, albuminuria, and reduced creatinine clearance were predictors of mortality (P < 0.05). Predictors of RRT were albuminuria (P < 0.001), reduced creatinine clearance (P < 0.001), and belonging to the 4th HbA1c quartile (P = 0.06). In Kaplan-Meier analysis, mortality was linearly associated with poor glycemia, whereas RRT incidence appeared to rise at a HbA1c threshold of approximately 8.5%. CONCLUSION/INTERPRETATION: In the Lainz T1DM cohort, 13.0% mortality and 5.6% RRT were directly associated with and more frequently found in poor glycemia, showing that good glycemic control is essential for the longevity and quality of life in T1DM.

In vivo and in vitro evidence for a hepatic modulation of the leptin signal in rats.

BACKGROUND: Leptin is primarily secreted by the adipose tissue. It binds not only to hypothalamic structures involved in energy regulation but also to many peripheral tissues including the liver. Leptin circulates in free and receptor-bound forms. Both components are differentially regulated under various pathophysiological conditions and serve different physiological functions. They are released from adipose tissue but previous data suggest an additional formation outside the fat compartment. Here we tested the contribution of the liver in binding and modulating leptin in the circulation. MATERIALS AND METHODS: In vivo experiments were performed with radioactive labelled leptin with and without pretreatment with unlabelled leptin in freely moving, chronic intravenously cannulated male rats. Livers were investigated by immunohistochemistry and in situ hybridization and immunoblotting was performed, followed by ex vivo liver perfusion studies with human recombinant leptin. RESULTS: In in vivo experiments radioactively labelled leptin (at low concentrations) is avidly bound to rat liver (greater than 80% of basal serum values 90 min following i.v. infusion). Pre-treatment with excess of unlabelled leptin in vivo revealed a rapid hepatic down-regulation of leptin receptor isoforms when tested by in situ hybridization, immunoblotting or immunohistochemistry. Ex vivo perfusion of rat liver with human recombinant leptin induced a dose- and time-dependent formation of receptor-bound leptin in the perfusate. CONCLUSIONS: The present data support an active role of the liver in the modulation of the leptin signal through different regulation of the soluble leptin receptor, the bound and free forms of the hormone, which may have important implications for leptin's central efficacy and the development of 'leptin resistance'.

Radiological progression of joint damage in a longitudinal cohort of early DMARD-treated rheumatoid arthritis patients followed for 10 years.

OBJECTIVE: The efficacy of DMARD therapy in rheumatoid arthritis (RA) can be judged by radiological analysis. This study aimed to determine the time-dependent progression of joint damage, acute-phase response, and rates of radiologic progression in early DMARD-treated RA patients over 10 years. PATIENTS AND METHODS: We evaluated outpatient records, and radiographs of hands and feet of 54 early RA patients on DMARDs for 10 years. Radiographs were quantified by the Larsen method using recently developed quantification software. RESULTS: Radiological damage attenuated, with disease progression from baseline to Year 10 [correlation coefficient (r)=0.95, probability (p)<0.001]. Radiographic scores progressed more rapidly during the first 5 years than thereafter. Cumulative erythrocyte sedimentation rate (ESR) was strongly correlated with radiological progression (p<0.001, r=0.88). CONCLUSION: Our findings reveal a higher amount of radiographic RA progression during the first years of DMARD treatment. Thus, our data provide strong evidence for the importance of both early DMARD therapy and continuous radiographic assessments in RA.

Direct and indirect effects of amino acids on hepatic glucose metabolism in humans.

AIM/HYPOTHESIS: The study was designed to examine the contribution of direct (substrate-mediated) and indirect (hormone-mediated) effects of amino acids on hepatic glucose metabolism in healthy men. METHODS: The protocols were: (i) CON+S (n=7): control conditions with somatostatin to inhibit endogenous hormone release resulting in fasting plasma concentrations of amino acids, insulin (approximately 28 pmol/l) and glucagon (approximately 65 ng/l), (ii) AA+S ( n=7): amino acid infusion-fasting insulinaemia-fasting glucagonaemia, (iii) GLUC+S ( n=6): fasting amino acids-fasting insulinaemia-hyperglucagonaemia (approximately 99 ng/l) and (iv) AA-S (n=5): amino acid infusion without somatostatin resulting in amino acid-induced hyperinsulinaemia (approximately 61 pmol/l)-hyperglucagonaemia (approximately 147 ng/l). Net glycogenolysis was calculated from liver glycogen concentrations using (13)C nuclear magnetic resonance spectroscopy. Total gluconeogenesis (GNG) was calculated by subtracting net glycogenolysis from endogenous glucose production (EGP) which was measured with [6,6-(2)H(2)]glucose. Net GNG was assessed with the (2)H(2)O method. RESULTS: During AA+S and GLUC+S, plasma glucose increased by about 50% (p<0.01) due to a comparable rise in EGP. This was associated with a 53-% (p<0.05) and a 65% increase (p<0.01) of total and net GNG during AA+S, whereas net glycogenolysis rose by 70% (p<0.001) during GLUC+S. During AA-S, plasma glucose remained unchanged despite nearly-doubled (p<0.01) total GNG. CONCLUSION/INTERPRETATION: Conditions of postprandial amino acid elevation stimulate secretion of insulin and glucagon without affecting glycaemia despite markedly increased gluconeogenesis. Impaired insulin secretion unmasks the direct gluconeogenic effect of amino acids and increases plasma glucose.

Effects of short-term leptin exposure on triglyceride deposition in rat liver.

Leptin has recently been suggested to play a role in the pathogenesis of hepatic steatosis. Consequently, this study was designed to examine the direct effects of portal leptin on the intrahepatic lipid contents in the postabsorptive state. Rat livers (n = 6 per group) were perfused in a recirculating system and portally infused with leptin (0.5 nmol/L, 5 nmol/L, and 25 nmol/L), insulin (10 nmol/L), leptin (5 nmol/L) plus insulin (10 nmol/L), glucagon (1 nmol/L), or vehicle (control). Intrahepatic contents of triglycerides, free cholesterol, cholesteryl esters, and free fatty acids were determined from the lipid extract of frozen livers by capillary gas chromatography. Short-term leptin infusion increased total triglycerides in a concentration-dependent (0.5 nmol/L: 2.8 +/- 0.4 mg/g, 5 nmol/L: 7.0 +/- 0.5 mg/g, 25 nmol/L: 8.3 +/- 1.0 mg/g) and time-dependent manner. Total triglycerides also rose during exposure to insulin plus leptin (7.2 +/- 0.6 mg/g) but fell during glucagon infusion (2.6 +/- 0.2 mg/g; control: 4.3 +/- 0.3 mg/g; P <.05). Leptin, insulin, and glucagon increased intrahepatic free cholesterol (P <.05). Free fatty acids were also higher during leptin exposure (0.5 nmol/L: 1.28 +/- 0.08 mg/g, 5 nmol/L: 0.47 +/- 0.01 mg/g, 25 nmol/L: 0.48 +/- 0.04 mg/g, control: 0.38 +/- 0.03 mg/g; P <.05). In conclusion, hyperleptinemia increases hepatic triglyceride content and may therefore contribute to hepatic steatosis in hyperleptinemic obese patients.