Dysglycemia and liver lipid content determine the relationship of insulin resistance with hepatic OXPHOS capacity in obesity.

BACKGROUND & AIMS: Hepatic mitochondrial respiration is higher in steatosis, but lower in overt type 2 diabetes. We hypothesized that hepatic OXPHOS capacity increases with a greater degree of insulin resistance in obesity, independent of other metabolic diseases. METHODS: We analysed 65 humans without diabetes (BMI 50±7 kg/m2, HbA1c 5.5±0.4%) undergoing bariatric surgery. MASLD stages were assessed by histology, whole-body insulin sensitivity (PREDIcted-M index) by oral glucose tolerance tests, and maximal ADP-stimulated mitochondrial OXPHOS capacity by high-resolution respirometry of liver samples. RESULTS: Prediabetes was present in 30 participants, and MASLD in 46 participants. Thereof, 25 had metabolic dysfunction-associated steatohepatitis (MASH), and seven had F2-F3 fibrosis. While simple regression did not detect an association of insulin sensitivity with hepatic OXPHOS capacity, interaction analyses revealed that the regression coefficient of OXPHOS capacity depended on fasting plasma glucose (FPG) and liver lipid content. Interestingly, the respective slopes were negative for FPG ≤100 mg/dl, but positive for FPG >100 mg/dl. Liver lipid content displayed similar behavior, with a threshold value of 24%. Post-challenge glycemia affected the association between insulin sensitivity and OXPHOS capacity normalized for citrate synthase activity. Presence of prediabetes affected hepatic insulin signaling, mitochondrial dynamics and fibrosis prevalence, while the presence of MASLD related to higher biomarkers of hepatic inflammation, cell damage and lipid peroxidation in people with normal glucose tolerance. CONCLUSIONS: Rising liver lipid contents and plasma glucose concentrations, even in the non-diabetic range, are associated with a progressive decline of hepatic mitochondrial adaptation in people with obesity and insulin resistance. CLINTRIALS. GOV IDENTIFIER: NCT01477957.

Association of thyroid function with non-alcoholic fatty liver disease in recent-onset diabetes.

BACKGROUND AND AIMS: Non-alcoholic fatty liver disease (NAFLD) has been linked to type 2 diabetes (T2D), but also to hypothyroidism. Nevertheless, the relationship between thyroid function and NAFLD in diabetes is less clear. This study investigated associations between free thyroxine (fT4) or thyroid-stimulating hormone (TSH) and NAFLD in recent-onset diabetes. METHODS: Participants with recent-onset type 1 diabetes (T1D, n = 358), T2D (n = 596) or without diabetes (CON, n = 175) of the German Diabetes Study (GDS), a prospective longitudinal cohort study, underwent Botnia clamp tests and assessment of fT4, TSH, fatty liver index (FLI) and in a representative subcohort 1 H-magnetic resonance spectroscopy. RESULTS: First, fT4 levels were similar between T1D and T2D (p = .55), but higher than in CON (T1D: p < .01; T2D: p < .001), while TSH concentrations were not different between all groups. Next, fT4 correlated negatively with FLI and positively with insulin sensitivity only in T2D (ß = -.110, p < .01; ß = .126, p < .05), specifically in males (ß = -.117, p < .05; ß = .162; p < .01) upon adjustments for age, sex and BMI. However, correlations between fT4 and FLI lost statistical significance after adjustment for insulin sensitivity (T2D: ß = -.021, p = 0.67; males with T2D: ß = -.033; p = .56). TSH was associated positively with FLI only in male T2D before (ß = .116, p < .05), but not after adjustments for age and BMI (ß = .052; p = .30). CONCLUSIONS: Steatosis risk correlates with lower thyroid function in T2D, which is mediated by insulin resistance and body mass, specifically in men, whereas no such relationship is present in T1D.

Precise glucose measurement in sodium fluoride-citrate plasma affects estimates of prevalence in diabetes and prediabetes.

OBJECTIVES: Estimates of glucose concentrations vary among types of blood samples, which impact on the assessment of diabetes prevalence. Guidelines recommend a conversion factor to calculate plasma glucose from measurements of glucose in whole blood. The American Diabetes Association recommends the use of blood drawing tubes containing sodium fluoride (NaF) and citrate, which have not yet been evaluated regarding possible differences in glucose concentration and conversion factors. Thus, we compared glucose measurements in NaF-citrate plasma and venous whole blood and estimated the impact of differences on diabetes and prediabetes prevalence. METHODS: Glucose differences were calculated by Bland-Altman analysis with pairwise comparison of glucose measurements from whole blood and NaF-citrate plasma (n=578) in clinical studies of the German Diabetes Center. Subsequently, we computed the impact of the glucose difference on diabetes and prediabetes prevalence in the population-based National Health and Nutrition Examination Survey (NHANES). RESULTS: Even upon conversion of whole blood to plasma glucose concentrations using the recommended conversion factor, mean glucose concentration difference remained 4.72 % higher in NaF-citrate plasma. Applying the higher glucose estimates, increases the population-based diabetes and prediabetes prevalence by 13.67 and 33.97 % or more than 7.2 and 13 million people in NHANES, respectively. Additional economic burden could be about 20 $ billion per year due to undiagnosed diabetes. CONCLUSIONS: The recommended conversion factor is not valid for NaF-citrate plasma. Systematic bias of glucose measurements due to sampling type leads to clinically relevant higher estimates of diabetes and prediabetes prevalence.

Association of dietary patterns with diabetes-related comorbidities varies among diabetes endotypes.

BACKGROUND AND AIMS: Differences of dietary pattern adherence across the novel diabetes endotypes are unknown. This study assessed adherence to pre-specified dietary patterns and their associations with cardiovascular risk factors, kidney function, and neuropathy among diabetes endotypes. METHODS AND RESULTS: The cross-sectional analysis included 765 individuals with recent-onset (67 %) and prevalent diabetes (33 %) from the German Diabetes Study (GDS) allocated into severe autoimmune diabetes (SAID, 35 %), severe insulin-deficient diabetes (SIDD, 3 %), severe insulin-resistant diabetes (SIRD, 5 %), mild obesity-related diabetes (MOD, 28 %), and mild age-related diabetes (MARD, 29 %). Adherence to a Mediterranean diet score (MDS), Dietary Approaches to Stop Hypertension (DASH) score, overall plant-based diet (PDI), healthful (hPDI) and unhealthful plant-based diet index (uPDI) was derived from a food frequency questionnaire and associated with cardiovascular risk factors, kidney function, and neuropathy using multivariable linear regression analysis. Differences in dietary pattern adherence between endotypes were assessed using generalized mixed models. People with MARD showed the highest, those with SIDD and MOD the lowest adherence to the hPDI. Adherence to the MDS, DASH, overall PDI, and hPDI was inversely associated with high-sensitivity C-reactive protein (hsCRP) among people with MARD (ß (95%CI): -9.18 % (-15.61; -2.26); -13.61 % (-24.17; -1.58); -19.15 % (-34.28; -0.53); -16.10 % (-28.81; -1.12), respectively). Adherence to the PDIs was associated with LDL cholesterol among people with SAID, SIRD, and MOD. CONCLUSIONS: Minor differences in dietary pattern adherence (in particular for hPDI) and associations with markers of diabetes-related complications (e.g. hsCRP) were observed between endotypes. So far, evidence is insufficient to derive endotype-specific dietary recommendations. TRIAL REGISTRATION: Clinicaltrials.gov: NCT01055093.

Serum neurofilament light chain: a novel biomarker for early diabetic sensorimotor polyneuropathy.

AIMS/HYPOTHESIS: No established blood-based biomarker exists to monitor diabetic sensorimotor polyneuropathy (DSPN) and evaluate treatment response. The neurofilament light chain (NFL), a blood biomarker of neuroaxonal damage in several neurodegenerative diseases, represents a potential biomarker for DSPN. We hypothesised that higher serum NFL levels are associated with prevalent DSPN and nerve dysfunction in individuals recently diagnosed with diabetes. METHODS: This cross-sectional study included 423 adults with type 1 and type 2 diabetes and known diabetes duration of less than 1 year from the prospective observational German Diabetes Study cohort. NFL was measured in serum samples of fasting participants in a multiplex approach using proximity extension assay technology. DSPN was assessed by neurological examination, nerve conduction studies and quantitative sensory testing. Associations of serum NFL with DSPN (defined according to the Toronto Consensus criteria) were estimated using Poisson regression, while multivariable linear and quantile regression models were used to assess associations with nerve function measures. In exploratory analyses, other biomarkers in the multiplex panel were also analysed similarly to NFL. RESULTS: DSPN was found in 16% of the study sample. Serum NFL levels increased with age. After adjustment for age, sex, waist circumference, height, HbA1c, known diabetes duration, diabetes type, cholesterol, eGFR, hypertension, CVD, use of lipid-lowering drugs and use of non-steroidal anti-inflammatory drugs, higher serum NFL levels were associated with DSPN (RR [95% CI] per 1-normalised protein expression increase, 1.92 [1.50, 2.45], p<0.0001), slower motor (all p<0.0001) and sensory (all p≤0.03) nerve conduction velocities, lower sural sensory nerve action potential (p=0.0004) and higher thermal detection threshold to warm stimuli (p=0.023 and p=0.004 for hand and foot, respectively). There was no evidence for associations between other neurological biomarkers and DSPN or nerve function measures. CONCLUSIONS/INTERPRETATION: Our findings in individuals recently diagnosed with diabetes provide new evidence associating higher serum NFL levels with DSPN and peripheral nerve dysfunction. The present study advocates NFL as a potential biomarker for DSPN.

Metabolic surgery-induced changes of the growth hormone system relate to improved adipose tissue function.

AIMS: Body weight loss improves insulin resistance and growth hormone secretion in obesity, which may be regulated by leptin according to preclinical studies. How changes in leptin, lipids and insulin sensitivity after bariatric (metabolic) surgery affect the human growth hormone system is yet unclear. PARTICIPANTS AND METHODS: People with obesity (OBE, n = 79, BMI 50.8 ± 6.3 kg/m2) were studied before, 2, 12, 24 and 52 weeks after metabolic surgery and compared to lean healthy humans (control; CON, n = 24, BMI 24.3 ± 3.1 kg/m2). Tissue-specific insulin sensitivity was assessed by hyperinsulinemic-euglycemic clamps with D-[6,6-2H2]glucose. Fasting leptin, growth hormone (GH), insulin-like growth factor 1 (IGF-1) and IGF-binding proteins (IGFBP1, IGFBP3) were measured using ELISA. RESULTS: At baseline, OBE exhibited higher glycemia and leptinemia as well as pronounced peripheral, adipose tissue and hepatic insulin resistance compared to CON. GH and IGFBP1 were lower, while IGF1 was comparable between groups. At 52 weeks, OBE had lost 33% body weight and doubled their peripheral insulin sensitivity, which was paralleled by continuous increases in GH, IGF-1 and IGFBP1 as well as decrease in leptin. The rise in GH correlated with reductions in free fatty acids, adipose tissue insulin resistance and insulinemia, but not with changes in body weight, peripheral insulin sensitivity, glycemia or leptinemia. The rise in IGF-1 correlated with reduction in high-sensitive C-reactive protein. CONCLUSION: Reversal of alterations of the GH-IGF-1 axis after surgically-induced weight loss is unlikely related to improved leptin secretion and/or insulin sensitivity, but is rather associated with restored adipose tissue function and reduced low-grade inflammation.

Effects of TM6SF2 rs58542926 polymorphism on hepatocellular lipids and insulin resistance in early type 2 diabetes.

BACKGROUND AND AIMS: Increased hepatocellular lipid content (HCL) is linked to insulin resistance, risk of type 2 diabetes and related complications. Conversely, a single-nucleotide polymorphism (TM6SF2EK; rs58542926) in the transmembrane 6 superfamily member 2-gene has been associated with nonalcoholic fatty liver disease (NAFLD), but lower cardiovascular risk. This case-control study tested the role of this polymorphism for tissue-specific insulin sensitivity during early course of diabetes. METHODS AND RESULTS: Males with recent-onset type 2 diabetes with (TM6SF2EK: n = 16) or without (TM6SF2EE: n = 16) the heterozygous TM6SF2-polymorphism of similar age and body mass index, underwent Botnia-clamps with [6,6-2H2]glucose to measure whole-body-, hepatic- and adipose tissue-insulin sensitivity. HCL was assessed with 1H-magnetic-resonance-spectroscopy. A subset of both groups (n = 24) was re-evaluated after 5 years. Despite doubled HCL, TM6SF2EK had similar hepatic- and adipose tissue-insulin sensitivity and 27% higher whole-body-insulin sensitivity than TM6SF2EE. After 5 years, whole-body-insulin sensitivity, HCL were similar between groups, while adipose tissue-insulin sensitivity decreased by 87% and 55% within both groups and circulating triacylglycerol increased in TM6SF2EE only. CONCLUSIONS: The TM6SF2-polymorphism rs58542926 dissociates HCL from insulin resistance in recent-onset type 2 diabetes, which is attenuated by disease duration. This suggests that diabetes-related metabolic alterations dominate over effects of the TM6SF2-polymorphism during early course of diabetes and NAFLD.

Differences in the prevalence of erectile dysfunction between novel subgroups of recent-onset diabetes.

AIMS/HYPOTHESIS: In men with diabetes, the prevalence of erectile dysfunction increases with advanced age and longer diabetes duration and is substantially higher in men with type 2 diabetes than those with type 1 diabetes. This study aimed to evaluate the prevalence of erectile dysfunction among the five novel subgroups of recent-onset diabetes and determine the strength of associations between diabetes subgroups and erectile dysfunction. METHODS: A total of 351 men with recent-onset diabetes (<1 year) from the German Diabetes Study baseline cohort and 124 men without diabetes were included in this cross-sectional study. Erectile dysfunction was assessed with the International Index of Erectile Function (IIEF) questionnaire. Poisson regression models were used to estimate associations between diabetes subgroups (each subgroup tested against the four other subgroups as reference) and erectile dysfunction (dependent binary variable), adjusting for variables used to define diabetes subgroups, high-sensitivity C-reactive protein and depression. RESULTS: The prevalence of erectile dysfunction was markedly higher in men with diabetes than in men without diabetes (23% vs 11%, p = 0.004). Among men with diabetes, the prevalence of erectile dysfunction was highest in men with severe insulin-resistant diabetes (SIRD) (52%), lowest in men with severe autoimmune diabetes (SAID) (7%), and intermediate in men with severe insulin-deficient diabetes (SIDD), mild obesity-related diabetes (MOD) and mild age-related diabetes (MARD) (31%, 18% and 29%, respectively). Men with SIRD had an adjusted RR of 1.93 (95% CI 1.04, 3.58) for prevalent erectile dysfunction (p = 0.038). Similarly, men with SIDD had an adjusted RR of 3.27 (95% CI 1.18, 9.10) (p = 0.023). In contrast, men with SAID and those with MARD had unadjusted RRs of 0.26 (95% CI 0.11, 0.58) (p = 0.001) and 1.52 (95% CI 1.04, 2.22) (p = 0.027), respectively. However, these associations did not remain statistically significant after adjustment. CONCLUSIONS/INTERPRETATION: The high RRs for erectile dysfunction in men with recent-onset SIRD and SIDD point to both insulin resistance and insulin deficiency as major contributing factors to this complication, suggesting different mechanisms underlying erectile dysfunction in these subgroups.

Mitochondrial respiration is decreased in visceral but not subcutaneous adipose tissue in obese individuals with fatty liver disease.

BACKGROUND & AIMS: Adipose tissue dysfunction is involved in the development of insulin resistance and is responsible for excessive lipid delivery to other organs such as the liver. We tested the hypothesis that impaired mitochondrial function is a common feature of subcutaneous (SAT) and visceral adipose tissue (VAT), but may differently contribute to adipose tissue insulin resistance (IR) in obesity, non-alcoholic fatty liver (NAFL) and steatohepatitis (NASH). METHODS: In this cross-sectional study, we analyzed tissue-specific insulin sensitivity using stable isotope dilution and hyperinsulinemic-normoglycemic clamp tests. We also assessed mitochondrial respiration, mRNA and protein expression, and tissue morphology in biopsies of SAT and VAT from obese humans without NAFL, with NAFL or with NASH (n = 22/group). RESULTS: Compared to individuals without liver disease, persons with NAFL and NASH had about 30% (p = 0.010) and 33% (p = 0.002) lower maximal mitochondrial respiration, respectively, in VAT, but not in SAT. The lower maximal mitochondrial respiration of VAT was associated with lower adipose tissue insulin sensitivity (ß = 0.985, p = 0.041) and with increased VAT protein expression of tumor necrosis factor A across all groups (ß = -0.085, p = 0.040). VAT from individuals with NASH was characterized by lower expression of oxidative phosphorylation complex IV (p = 0.042) and higher mRNA expression of the macrophage marker CD68 (p = 0.002) than VAT from participants without NAFL. CONCLUSIONS: Humans with non-alcoholic fatty liver disease have distinct abnormalities of VAT energy metabolism, which correlate with adipose tissue dysfunction and may favor progression of NAFL to NASH. LAY SUMMARY: Adipose tissue (commonly called body fat) can be found under the skin (subcutaneous) or around internal organs (visceral). Dysfunction of adipose tissue can cause insulin resistance and lead to excess delivery of fat to other organs such as the liver. Herein, we show that dysfunction specifically in visceral adipose tissue was associated with fatty liver disease. CLINICAL TRIAL NUMBER: NCT01477957.

Socio-economic inequalities in glycaemic control in recently diagnosed adults with type 1 and type 2 diabetes.

BACKGROUND AND AIMS: It is unclear whether socio-economic status (SES) is associated with glycaemic control in people with recently diagnosed diabetes. The aim was to investigate whether SES is related to haemoglobin A1c (HbA1c) during the first year after diagnosis in people with type 1 and type 2 diabetes and if metabolic, quality of care or mental factors may explain the association. METHODS: In the German Diabetes Study, people with type 1 (n = 274, median age 36 [25th; 75th percentile: 28; 48] years) and type 2 diabetes (n = 424, 54 [47; 60] years) underwent detailed metabolic characterisation within the first year after diagnosis. SES was documented using a standardised questionnaire. Associations between SES and HbA1c were assessed using multivariable linear regression and restricted cubic spline regression analyses. Additional covariables were patient characteristics, laboratory measurements, health behaviour, quality of care and depression variables. Models were separately fitted for diabetes type, SES and its dimensions (income, education, occupation). RESULTS: Higher SES score was associated with lower HbA1c (-0.7 mmol/mol per unit increase in SES, 95% CI: -1.1; -0.2 mmol/mol [-0.1%, 95% CI: -0.1; 0.0%]) in people with type 1 diabetes. Included covariates did not attenuate this association. In people with type 2 diabetes, effect estimates were close to zero indicating no relevant difference. CONCLUSION: Socio-economic inequalities in HbA1c already exist during the first year after diagnosis in people with type 1 diabetes. The absence of association between glycaemic control and SES in type 2 diabetes could be due to the lower complexity of diabetes therapy compared to type 1 diabetes.

Progression and regression of nerve fibre pathology and dysfunction early in diabetes over 5 years.

It has traditionally been suggested that the early development of diabetic sensorimotor polyneuropathy (DSPN) is characterized by predominant and progressive injury to small nerve fibres followed by large fibre impairment. We alternatively hypothesized that small and large fibre damage due to DSPN in type 1 and type 2 diabetes could develop in parallel and may not only be progressive but also reversible. Participants from the German Diabetes Study baseline cohort with recent-onset type 1/type 2 diabetes (n = 350/570) and age-matched glucose-tolerant control individuals (Control 1/Control 2: n = 114/190) were assessed using nerve conduction studies, thermal detection thresholds, vibration perception thresholds, neuropathy symptom scores, neuropathy disability scores and intraepidermal nerve fibre density (IENFD) in skin biopsies (type 1/type 2 diabetes: n = 102/226; Control 1/Control 2: n = 109/208). Subsets of participants with type 1/type 2 diabetes were followed for 5 years (n = 184/307; IENFD subset: n = 18/69). DSPN was defined by the Toronto Consensus criteria. At baseline, DSPN was present in 8.1% and 13.3% of the type 1 and type 2 diabetes groups, respectively. The most frequently abnormal tests in the lower limbs below or above the 2.5th and 97.5th centiles of the controls were the IENFD (13.7%) and individual nerve conduction studies (up to 9.4%) in type 1 diabetes participants and IENFD (21.8%), malleolar vibration perception thresholds (17.5%), and individual nerve conduction studies (up to 11.8%) in those with type 2 diabetes, whereas thermal detection threshold abnormalities did not differ between the control and diabetes groups. After 5 years, the highest progression rates from the normal to the abnormal range in type 2 diabetes participants were found for IENFD (18.8%) by -4.1 ± 2.8 fibres/mm, malleolar vibration perception threshold (18.6%) by 9.1 ± 20.2 µm and nerve conduction studies (15.0%) by 3.7 ± 1.5 points, while vice versa the highest regression rates were observed for neuropathy disability scores (11.2%) by -3.1 ± 1.3 points, sural nerve amplitudes (9.1%) by 4.7 ± 3.0 µV, IENFD (8.7%) by 1.4 ± 1.3 fibres/mm, and neuropathy symptom scores (8.2%) by -5.8 ± 1.6 points. In type 1 diabetes participants, no major progression was seen after 5 years, but subclinical DSPN regressed in 10.3%. These findings point to early parallel damage to both small and large nerve fibres in well-controlled recent-onset type 2 and, to a lesser extent, type 1 diabetes. After 5 years, peripheral nerve morphology and function and clinical measures progress to the abnormal range in type 2 diabetes, but initial nerve alterations are also reversible to a meaningful degree.

Association of cardiac autonomic dysfunction with higher levels of plasma lipid metabolites in recent-onset type 2 diabetes.

AIMS/HYPOTHESIS: Emerging evidence suggests that in addition to hyperglycaemia, dyslipidaemia could represent a contributing pathogenetic factor to diabetic neuropathy, while obesity and insulin resistance play a role in the development of diabetic cardiac autonomic neuropathy (CAN) characterised by reduced heart rate variability (HRV), particularly in type 2 diabetes. We hypothesised that distinct lipid metabolites are associated with diminished HRV in recent-onset type 2 diabetes rather than type 1 diabetes. METHODS: We analysed 127 plasma lipid metabolites (11 acylcarnitines, 39 NEFA, 12 sphingomyelins (SMs), 56 phosphatidylcholines and nine lysophosphatidylcholines) using MS in participants from the German Diabetes Study baseline cohort recently diagnosed with type 1 (n = 100) and type 2 diabetes (n = 206). Four time-domain HRV indices (number of normal-to-normal (NN) intervals >50 ms divided by the number of all NN intervals [pNN50]; root mean square of successive differences [RMSSD]; SD of NN intervals [SDNN]; and SD of differences between adjacent NN intervals) and three frequency-domain HRV indices (very-low-frequency [VLF], low-frequency [LF] and high-frequency [HF] power spectrum) were computed from NN intervals recorded during a 3 h hyperinsulinaemic-euglycaemic clamp at baseline and in subsets of participants with type 1 (n = 60) and type 2 diabetes (n = 95) after 5 years. RESULTS: In participants with type 2 diabetes, after Bonferroni correction and rigorous adjustment, SDNN was inversely associated with higher levels of diacyl-phosphatidylcholine (PCaa) C32:0, PCaa C34:1, acyl-alkyl-phosphatidylcholine (PCae) C36:0, SM C16:0 and SM C16:1. SD of differences between NN intervals was inversely associated with PCaa C32:0, PCaa C34:1, PCaa C34:2, PCae C36:0 and SM C16:1, and RMSSD with PCae C36:0. For VLF power, inverse associations were found with PCaa C30:0, PCaa C32:0, PCaa C32:1, PCaa C34:2 and SM C16:1, and for LF power inverse associations were found with PCaa C32:0 and SM C16:1 (r = -0.242 to r = -0.349; p ≤ 0.0005 for all correlations). In contrast, no associations of lipid metabolites with measures of cardiac autonomic function were noted in participants recently diagnosed with type 1 diabetes. After 5 years, HRV declined due to ageing rather than diabetes, whereby prediction analyses for lipid metabolites were hampered. CONCLUSIONS/INTERPRETATION: Higher plasma levels of specific lipid metabolites are closely linked to cardiac autonomic dysfunction in recent-onset type 2 diabetes but not type 1 diabetes, suggesting a role for perturbed lipid metabolism in the early development of CAN in type 2 diabetes. Graphical abstract.

Increased spontaneous CCL2 (MCP-1) and CCL5 (RANTES) secretion in vitro in LADA compared to type 1 diabetes and type 2 diabetes: Action LADA 14.

AIMS: Immune-mediated type 1 diabetes (T1D) in adulthood and latent autoimmune diabetes in adults (LADA) share similar pathological mechanisms but differ clinically in disease progression. The aim of this study was to acquire insights into spontaneous and stimulated chemokine secretion of immune cells in different diabetes types. MATERIALS AND METHODS: We investigated in vitro spontaneous, mitogen (PI) and antigen (HSP60, p277, pGAD, pIA2) stimulated chemokine secretion of leucocytes from patients with T1D (n = 32), LADA (n = 22), type 2 diabetes (T2D; n = 49), and glucose-tolerant individuals (n = 13). Chemokine concentration in supernatants was measured for CCL2 (MCP-1), CXCL10 (IP10) and CCL5 (RANTES) using a multiplex bead array assay. RESULTS: Spontaneous secretion of CCL2 and CCL5 were higher in LADA compared to T1D and T2D (all p < 0.05) while CXCL10 was similar in the groups. Mitogen-stimulated secretion of CCL2 in LADA was lower compared to T1D and T2D (all p < 0.05) while CXCL10 and CCL5 were similar in all groups. Upon stimulation with pIA2 the secretion of CCL2 in LADA was lower compared to T2D (p < 0.05). Spontaneous CXCL10 secretion in LADA was positively associated with body mass index (r2  = 0.35; p = 0.0035) and C-peptide (r2  = 0.30; p = 0.009). CONCLUSIONS: Chemokine secretion is altered between different diabetes types. Increased spontaneous secretion of CCL2 and CCL5 and decreased secretion of CCL2, upon stimulation with PI and pIA2, in LADA compared to T1D and T2D could reflect altered immune responsiveness in LADA patients in association with their slower clinical progression compared to insulin dependence.

A variant of the glucose transporter gene SLC2A2 modifies the glycaemic response to metformin therapy in recently diagnosed type 2 diabetes.

AIMS/HYPOTHESIS: The aim of this study was to investigate the modifying effect of the glucose transporter (GLUT2) gene SLC2A2 (rs8192675) variant on the glycaemic response to metformin in individuals recently diagnosed with type 2 diabetes. METHODS: Individuals with type 2 diabetes (n = 508) from the prospective German Diabetes Study (age [mean ± SD] 53 ± 10 years; 65% male; BMI 32 ± 6 kg/m2, metformin use 57%) underwent detailed metabolic characterisation (hyperinsulinaemic-euglycaemic clamp, IVGTT) during the first year after diagnosis. Participants provided self-reported data from the time of diagnosis. The change in fasting glucose was assessed in relation to SLC2A2 genotype and glucose-lowering treatment using two-way ANCOVA with gene×treatment interactions adjusted for age, sex, BMI and diabetes duration. RESULTS: The C variant allele of rs8192675 was associated with a higher prevalence of diabetes symptoms at diabetes diagnosis. In the metformin monotherapy group only, patients with a C allele showed a larger adjusted blood glucose reduction during the first year after diabetes diagnosis than patients with the TT genotype (6.3 mmol/l vs 3.9 mmol/l; genotype difference 2.4 mmol/l, p = 0.02; p value for genotype interaction [metformin monotherapy vs non-pharmacological therapy] <0.01). The greater decline in fasting glucose (CC/CT vs TT) in metformin monotherapy persisted after further adjusting for glucose values at diagnosis (genotype difference 1.0 mmol/l, p = 0.01; genotype×treatment interaction p = 0.06). CONCLUSIONS/INTERPRETATION: The variant rs8192675 in the SLC2A2 gene (C allele) is associated with an improved glucose response to metformin monotherapy during the first year after diagnosis in type 2 diabetes. TRIAL REGISTRATION: ClinicalTrials.gov NCT01055093.

Associations between inflammation-related biomarkers and depressive symptoms in individuals with recently diagnosed type 1 and type 2 diabetes.

Depressive disorders represent a frequent comorbidity of both type 1 (T1D) and type 2 diabetes (T2D). Inflammation-related processes have been implicated in the development of both diabetes and depression. This study aimed to investigate whether biomarkers of subclinical inflammation were associated with depressive symptoms in individuals with recently diagnosed diabetes and if such associations differed by diabetes type. This cross-sectional study was based on 295 individuals with T2D (67% men, mean age 53years) and 139 individuals with T1D (60% men, mean age 36years) of the German Diabetes Study. The main inclusion criterion was a known disease duration of <1year. Depressive symptoms were assessed with the Allgemeine Depressionsskala, Langversion (ADS-L) questionnaire, the German version of the Center for Epidemiological Studies Depression scale (CES-D) questionnaire. Associations between biomarkers of subclinical inflammation and the ADS-L as continuous score were assessed using multiple linear regression models adjusting for age, sex, body mass index, HbA1c, lipids, hypertension, medication and comorbidities. Serum high-sensitivity C-reactive protein (hsCRP) and the ratio of high-molecular-weight (HMW)/total adiponectin were positively associated with ADS-L in T2D (both P<0.01), but not in T1D. In contrast, serum levels of soluble intercellular adhesion molecule (sICAM)-1 were positively associated with ADS-L only in T1D (P=0.035). The latter association was significantly different between both diabetes types (Pinteraction=0.036). No associations were observed for interleukin (IL)-6, IL-18 and soluble E-selectin. Only the association between HMW/total adiponectin and ADS-L in T2D remained significant after correction for multiple testing. In conclusion, our study shows that the ratio HMW/total adiponectin is associated with depressive symptoms in individuals with recently diagnosed T2D. It also provides suggestive evidence that further biomarkers of subclinical inflammation and endothelial activation may be associated with depressive symptoms in individuals with recently diagnosed T1D and T2D.

Impact of insulin sensitivity, beta-cell function and glycaemic control on initiation of second-line glucose-lowering treatment in newly diagnosed type 2 diabetes.

AIMS: The aim of this study was to investigate whether insulin sensitivity, beta-cell function or glycaemic control at diagnosis predict initiation of second-line treatment in newly diagnosed type 2 diabetes. RESEARCH DESIGN AND METHODS: Type 2 diabetes patients (n = 138) undergoing initial metformin monotherapy (age [mean ± SD], 52 ± 10 years; 67% males; BMI, 32 ± 6 kg/m2 ) from the prospective German Diabetes Study cohort (n = 398) were included. Patients remained under care of their general practitioners, yet underwent detailed metabolic characterization after diabetes diagnosis for study purposes (hyperinsulinemic-euglycemic clamp, M value; i.v. glucose tolerance test, incremental C-peptide area under the curve0-60 minutes, CP iAUC). The associations of baseline M value, CP iAUC, fasting glucose and HbA1c with time to second-line therapy were assessed using parametric survival analysis, accounting for interval-censoring. RESULTS: Second-line treatment was initiated in 26% of newly diagnosed type 2 diabetes patients within the first 3.3 years after diagnosis, using mostly DPP-4 inhibitors or GLP-1 receptor agonists (64%). In age-, sex- and BMI-adjusted survival models, higher baseline HbA1c and fasting glucose values were associated with earlier treatment intensification. Lower baseline M value and C-peptide secretion (CP iAUC) were also related to an earlier initiation of second-line treatment. In the best multivariable model, baseline HbA1c ≥ 7% (hazard ratio, HR; 95% CI: 3.18; 1.35-7.50) and fasting glucose ≥140 mg/dL (HR, 2.45; 95% CI, 1.04-5.78) were associated with shorter time to second-line therapy, adjusting for age, sex and BMI. CONCLUSIONS: Baseline hyperglycaemia is a strong predictor of requirement of early intensification of glucose-lowering therapy in newly diagnosed type 2 diabetes.

Metabolic flexibility and oxidative capacity independently associate with insulin sensitivity in individuals with newly diagnosed type 2 diabetes.

AIMS/HYPOTHESIS: Both inherited and acquired insulin resistance have been associated with abnormal muscle mitochondrial function. At whole-body level, maximal oxygen uptake ([Formula: see text]) and/or metabolic flexibility (as given by ΔRQ) reflect certain features of mitochondrial function. This study tests the hypotheses (1) that [Formula: see text] and ΔRQ correlate tightly with each other and with insulin sensitivity and (2) that glycaemia, lipidaemia or subclinical inflammation would explain such relationships. METHODS: Near-normoglycaemic individuals with type 2 diabetes mellitus (n = 136) with a short known disease duration (<12 months) underwent cycling spiroergometry, indirect calorimetry and hyperinsulinaemic-euglycaemic clamp tests. RESULTS: Both [Formula: see text] (r = 0.39, p < 0.0001) and ΔRQ (r = 0.32, p < 0.0001) correlated positively with whole-body insulin sensitivity, even after adjusting for anthropometric variables, glycaemia and glucose-lowering medication, but not after adjusting for NEFA. [Formula: see text] further correlated negatively with circulating high-sensitivity C-reactive protein concentration. However, [Formula: see text] did not relate to ΔRQ, even after adjusting for whole-body insulin sensitivity. CONCLUSIONS/INTERPRETATION: Oxidative capacity and metabolic flexibility are independent determinants of insulin sensitivity but are influenced by circulating NEFA in recent-onset type 2 diabetes. ClinicalTrial.gov registration no: NCT01055093.

Associations between explorative dietary patterns and serum lipid levels and their interactions with ApoA5 and ApoE haplotype in patients with recently diagnosed type 2 diabetes.

AIMS: In patients with type 2 diabetes (T2D), responsiveness of serum lipid concentrations to dietary patterns may vary by genotype. The aims of the present study were to identify explorative dietary patterns and to examine their independent associations with serum lipid levels and interactions with apolipoprotein (Apo)A5 and ApoE variants among patients recently diagnosed with T2D. METHODS: Within a cross-sectional analysis, participants of the German Diabetes Study (n = 348) with mean T2D duration of 6 months were investigated for fasting serum lipid levels, ApoA5 and ApoE genotypes; food consumption frequencies were assessed by a food propensity questionnaire. Dietary patterns were derived using principal component analysis (PCA) and reduced rank regression (RRR), which extracts patterns explaining variation in serum lipid concentrations. RESULTS: PCA yielded interpretable dietary patterns which were, however, not related to serum lipid levels. Relevance of the RRR patterns varied by genotype: a preferred consumption of fruit gum, fruit juice, and potato dumpling, whilst avoiding fruits and vegetables independently associated with higher triglyceride levels among ApoA5*2. Patients in the highest compared to the lowest tertile of pattern adherence had 99 % higher triglycerides. Lower consumption frequencies of butter, cream cake, French fries, or high-percentage alcoholic beverages were independently related to lower LDL-cholesterol among ApoE2 carriers, with those in the highest compared to the lowest tertile of pattern adherence having 40 % lower LDL-cholesterol (both Pinteraction < 0.05). CONCLUSIONS: Our explorative data analyses suggest that associations of dietary patterns with triglycerides and LDL-cholesterol differ by ApoA5 and ApoE haplotype in recently diagnosed T2D. Trial registration Clinicaltrials.gov: NCT01055093. Date of registration: January 22, 2010 (retrospectively registered). Date of enrolment of first participant to the trial: September 2005.

Cohort profile: the German Diabetes Study (GDS).

BACKGROUND: The German Diabetes Study (GDS) is a prospective longitudinal cohort study describing the impact of subphenotypes on the course of the disease. GDS aims at identifying prognostic factors and mechanisms underlying the development of related comorbidities. STUDY DESIGN AND METHODS: The study comprises intensive phenotyping within 12 months after clinical diagnosis, at 5-year intervals for 20 years and annual telephone interviews in between. Dynamic tests, including glucagon, mixed meal, intravenous glucose tolerance and hyperinsulinemic clamp tests, serve to assess beta-cell function and tissue-specific insulin sensitivity. Magnetic resonance imaging and multinuclei spectroscopy allow quantifying whole-body fat distribution, tissue-specific lipid deposition and energy metabolism. Comprehensive analyses of microvascular (nerve, eye, kidney) and macrovascular (endothelial, cardiorespiratory) morphology and function enable identification and monitoring of comorbidities. The GDS biobank stores specimens from blood, stool, skeletal muscle, subcutaneous adipose tissue and skin for future analyses including multiomics, expression profiles and histology. Repeated questionnaires on socioeconomic conditions, patient-reported outcomes as quality of life, health-related behavior as physical activity and nutritional habits are a specific asset of GDS. This study will recruit 3000 patients and a group of humans without familiy history of diabetes. 237 type 1 and 456 type 2 diabetes patients have been already included.

Pancreatic adipose tissue infiltration, parenchymal steatosis and beta cell function in humans.

AIMS/HYPOTHESIS: This study aimed to perform a comprehensive analysis of interlobular, intralobular and parenchymal pancreatic fat in order to assess their respective effects on beta cell function. METHODS: Fifty-six participants (normal glucose tolerance [NGT] (n = 28), impaired fasting glucose (IFG) and/or impaired glucose tolerance (IGT) (n = 14) and patients with type 2 diabetes (n = 14)) underwent a frequent-sampling OGTT and non-invasive magnetic resonance imaging (MRI; whole-body and pancreatic) and proton magnetic resonance spectroscopy ((1)H-MRS; liver and pancreatic fat). Total pancreatic fat was assessed by a standard 2 cm(3) (1)H-MRS method, intralobular fat by 1 cm(3) (1)H-MRS that avoided interlobular fat within modified DIXON (mDIXON) water images, and parenchymal fat by a validated mDIXON-MRI fat-fraction method. RESULTS: Comparison of (1)H-MRS techniques revealed an inhomogeneous distribution of interlobular and intralobular adipose tissue, which increased with decreasing glucose tolerance. mDIXON-MRI measurements provided evidence against uniform steatosis, revealing regions of parenchymal tissue void of lipid accumulation in all participants. Total (r = 0.385, p < 0.01) and intralobular pancreas adipose tissue infiltration (r = 0.310, p < 0.05) positively associated with age, but not with fasting or 2 h glucose levels, BMI or visceral fat content (all p > 0.5). Furthermore, no associations were found between total and intralobular pancreatic adipose tissue infiltration and insulin secretion or beta cell function within NGT, IFG/IGT or patients with type 2 diabetes (all p > 0.2). CONCLUSIONS/INTERPRETATION: The pancreas does not appear to be another target organ for abnormal endocrine function because of ectopic parenchymal fat storage. No relationship was found between pancreatic adipose tissue infiltration and beta cell function, regardless of glucose tolerance status.