Analysis of type 2 diabetes heterogeneity with a tree-like representation: insights from the prospective German Diabetes Study and the LURIC cohort.

BACKGROUND: Heterogeneity in type 2 diabetes can be represented by a tree-like graph structure by use of reversed graph-embedded dimensionality reduction. We aimed to examine whether this approach can be used to stratify key pathophysiological components and diabetes-related complications during longitudinal follow-up of individuals with recent-onset type 2 diabetes. METHODS: For this cohort analysis, 927 participants aged 18-69 years from the German Diabetes Study (GDS) with recent-onset type 2 diabetes were mapped onto a previously developed two-dimensional tree based on nine simple clinical and laboratory variables, residualised for age and sex. Insulin sensitivity was assessed by a hyperinsulinaemic-euglycaemic clamp, insulin secretion was assessed by intravenous glucose tolerance test, hepatic lipid content was assessed by 1 H magnetic resonance spectroscopy, serum interleukin (IL)-6 and IL-18 were assessed by ELISA, and peripheral and autonomic neuropathy were assessed by functional and clinical measures. Participants were followed up for up to 16 years. We also investigated heart failure and all-cause mortality in 794 individuals with type 2 diabetes undergoing invasive coronary diagnostics from the Ludwigshafen Risk and Cardiovascular Health (LURIC) cohort. FINDINGS: There were gradients of clamp-measured insulin sensitivity (both dimensions: p<0·0001) and insulin secretion (pdim1<0·0001, pdim2=0·00097) across the tree. Individuals in the region with the lowest insulin sensitivity had the highest hepatic lipid content (n=205, pdim1<0·0001, pdim2=0·037), pro-inflammatory biomarkers (IL-6: n=348, pdim1<0·0001, pdim2=0·013; IL-18: n=350, pdim1<0·0001, pdim2=0·38), and elevated cardiovascular risk (nevents=143, pdim1=0·14, pdim2<0·00081), whereas individuals positioned in the branch with the lowest insulin secretion were more prone to require insulin therapy (nevents=85, pdim1=0·032, pdim2=0·12) and had the highest risk of diabetic sensorimotor polyneuropathy (nevents=184, pdim1=0·012, pdim2=0·044) and cardiac autonomic neuropathy (nevents=118, pdim1=0·0094, pdim2=0·06). In the LURIC cohort, all-cause mortality was highest in the tree branch showing insulin resistance (nevents=488, pdim1=0·12, pdim2=0·0032). Significant gradients differentiated individuals having heart failure with preserved ejection fraction from those who had heart failure with reduced ejection fraction. INTERPRETATION: These data define the pathophysiological underpinnings of the tree structure, which has the potential to stratify diabetes-related complications on the basis of routinely available variables and thereby expand the toolbox of precision diabetes diagnosis. FUNDING: German Diabetes Center, German Federal Ministry of Health, Ministry of Culture and Science of the state of North Rhine-Westphalia, German Federal Ministry of Education and Research, German Diabetes Association, German Center for Diabetes Research, European Community, German Research Foundation, and Schmutzler Stiftung.

Intramyocellular Triglyceride Content During the Early Course of Type 1 and Type 2 Diabetes.

Intramyocellular lipid content (IMCL) is elevated in insulin-resistant humans, but it changes over time, and relationships with comorbidities remain unclear. We examined IMCL during the initial course of diabetes and its associations with complications. Participants of the German Diabetes Study (GDS) with recent-onset type 1 (n = 132) or type 2 diabetes (n = 139) and glucose-tolerant control subjects (n = 128) underwent 1H-MRS to measure IMCL and muscle volume, whole-body insulin sensitivity (hyperinsulinemic-euglycemic clamps; M-value), and cycling spiroergometry (VO2max). Subgroups underwent the same measurements after 5 years. At baseline, IMCL was ∼30% higher in type 2 diabetes than in other groups independently of age, sex, BMI, and muscle volume. In type 2 diabetes, the M-value was ∼36% and ∼62% lower compared with type 1 diabetes and control subjects, respectively. After 5 years, the M-value decreased by ∼29% in type 1 and ∼13% in type 2 diabetes, whereas IMCL remained unchanged. The correlation between IMCL and M-value in type 2 diabetes at baseline was modulated by VO2max. IMCL also associated with microalbuminuria, the Framingham risk score for cardiovascular disease, and cardiac autonomic neuropathy. Changes in IMCL within 5 years after diagnosis do not mirror the progression of insulin resistance in type 2 diabetes but associate with early diabetes-related complications. ARTICLE HIGHLIGHTS: Intramyocellular lipid content (IMCL) can be elevated in insulin-resistant humans, but its dynamics and association with comorbidities remain unclear. Independently of age, sex, body mass, and skeletal muscle volume, IMCL is higher in recent-onset type 2, but not type 1 diabetes, and remains unchanged within 5 years, despite worsening insulin resistance. A degree of physical fitness modulates the association between IMCL and insulin sensitivity in type 2 diabetes. Whereas higher IMCL associates with lower insulin sensitivity in people with lower physical fitness, there is no association between IMCL and insulin sensitivity in those with higher degree of physical fitness. IMCL associates with progression of microalbuminuria, cardiovascular disease risk, and cardiac autonomic neuropathy.

Comorbidities in Recent-Onset Adult Type 1 Diabetes: A Comparison of German Cohorts.

Aims: Restrictive exclusion criteria from different study populations may limit the generalizability of the observations. By comparing two differently designed German cohorts, we assessed the prevalence of cardiovascular risk factors and diabetes-related complications in recent-onset adult type 1 diabetes. Methods: This study evaluated 1511 persons with type 1 diabetes of the prospective diabetes follow-up registry (DPV) and 268 volunteers of the prospective observational German Diabetes Study (GDS) with a known diabetes duration <1 year. Participants had similar age (36 years), sex distribution (41% female) and BMI (26 kg/m2) in both cohorts. Results: The average HbA1c was 6.4 ± 0.8% in the GDS and 7.0 ± 1.1% in the DPV. Prevalence of hypertension (24%) was similar, while more DPV participants had dyslipidemia and lipid-lowering medication than GDS participants (77% vs. 41% and 7% vs. 2%, respectively; p<0.05). Prevalence of retinopathy and nephropathy was higher in DPV compared to GDS participants (10% vs. 3% and 18% vs. 7%, respectively; p<0.001). Conclusions: Diabetic nephropathy and retinopathy are the most frequent complications in type 1 diabetes, affecting up to every 10th patient within the first year after diagnosis, underlining the need for more stringent risk factor management already at the time of diagnosis of type 1 diabetes.

Improving insulin sensitivity, liver steatosis and fibrosis in type 2 diabetes by a food-based digital education-assisted lifestyle intervention program: a feasibility study.

PURPOSE: Recent trials demonstrated remission of type 2 diabetes and non-alcoholic fatty liver disease (NAFLD) following formula diet-induced weight loss. To improve the outreach for populations in need, many mobile health apps targeting weight loss have been developed with limited scientific evaluation of these apps. The present feasibility study investigated the effects of a novel approach incorporating a regular 'whole food-based' low-calorie diet combined with app-based digital education and behavioral change program on glucose metabolism and disease management. METHODS: Twenty-four individuals with type 2 diabetes followed this approach supported by weekly coaching calls for 12 weeks. Phenotyping included bioimpedance analysis, mixed-meal tolerance test, magnetic resonance spectroscopy and transient elastography for assessing liver fat content and liver stiffness. RESULTS: Over 12 weeks, participants reduced their body weight by 9% (97 ± 13 to 88 ± 12 kg), body mass index (BMI; 33 ± 5 to 29 ± 4 kg/m2), total fat mass (31 ± 10 to 27 ± 10%) (all p < 0.01) and liver fat by 50% alongside with decreased liver stiffness. Target HbA1c (< 6.5%) was achieved by 38% and resolution of NAFLD (liver fat content < 5.6%) was observed in 30% of the participants. CONCLUSION: This novel approach combining digital education with a low-calorie diet results in effective improvements of body weight, glycemic control and NAFLD and could complement existing care for patients with type 2 diabetes. TRIAL REGISTRATION: NCT04509245.

Role of Patatin-Like Phospholipase Domain-Containing 3 Gene for Hepatic Lipid Content and Insulin Resistance in Diabetes.

OBJECTIVE: The rs738409(G) single nucleotide polymorphism (SNP) in the patatin-like phospholipase domain-containing 3 (PNPLA3) gene associates with increased risk and progression of nonalcoholic fatty liver disease (NAFLD). As the recently described severe insulin-resistant diabetes (SIRD) cluster specifically relates to NAFLD, this study examined whether this SNP differently associates with hepatic lipid content (hepatocellular lipids [HCL]) and insulin sensitivity in recent-onset diabetes. RESEARCH DESIGN AND METHODS: A total of 917 participants in the German Diabetes Study (GDS) underwent genotyping, hyperinsulinemic-euglycemic clamps with stable isotopic tracer dilution, and MRS. RESULTS: The G allele associated positively with HCL (ß = 0.36, P < 0.01), independent of age, sex, and BMI across the whole cohort, but not in the individual clusters. Those with SIRD exhibited lowest whole-body insulin sensitivity compared with those with severe insulin-deficient (SIDD), moderate obesity-related (MOD), moderate age-related (MARD), and severe autoimmune diabetes (SAID) clusters (all P < 0.001). Interestingly, the SIRD group presented with higher prevalence of the rs738409(G) SNP compared with other clusters and the glucose-tolerant control group (P < 0.05). HCL was higher in the SIRD group (median 13.6% [1st quartile 5.8; 3rd quartile 19.1] compared with the MOD (6.4 % [2.1; 12.4], P < 0.05), MARD (3.0% [1.0; 7.9], P < 0.001), SAID (0.4% [0.0; 1.5], P < 0.001), and glucose-tolerant (0.9% [0.4; 4.9), P < 0.001) group. Although the PNPLA3 polymorphism did not directly associate with whole-body insulin sensitivity in SIRD, the G-allele carriers had higher circulating free fatty acid concentrations and greater adipose tissue insulin resistance compared with noncarriers (both P < 0.001). CONCLUSIONS: Members of the SIRD cluster are more frequently carriers of the rs738409(G) variant. The SNP-associated adipose tissue insulin resistance and excessive lipolysis may contribute to their NAFLD.

Vitamin B12 and Folate Concentrations in Recent-onset Type 2 Diabetes and the Effect of Metformin Treatment.

CONTEXT: Vitamin B12 and folate deficiency are not only linked to hematological, neurological, and cardiovascular diseases, but are also associated with insulin resistance. Metformin can decrease vitamin B12 and folate concentrations. OBJECTIVE: To examine (1) effects of short-term metformin treatment on serum holotranscobalamin (holoTC) and folate and (2) their association with insulin sensitivity in recent-onset type 2 diabetes. DESIGN: This cross-sectional analysis comprised patients (known disease duration <12 months) on metformin monotherapy (MET, n = 123, 81 males, 53 ±â€…12 years) or nonpharmacological treatment (NPT, n = 126, 77 males, 54 ±â€…11 years) of the German Diabetes Study. MAIN OUTCOME MEASURES: HoloTC (enzyme-linked immunosorbent assay), cobalamin, and folate (electrochemiluminescence); beta-cell function and whole-body insulin sensitivity, measured during fasting (HOMA-B, HOMA-IR) and intravenous glucose tolerance tests combined with hyperinsulinemic-euglycemic clamp tests. RESULTS: HoloTC (105.4 [82.4, 128.3] vs 97 [79.7, 121.9] pmol/L) and folate concentrations (13.4 [9.3, 19.3] vs 12.7 [9.3, 22.0] nmol/L) were similar in both groups. Overall, holoTC was not associated with fasting or glucose-stimulated beta-cell function and insulin-stimulated glucose disposal. Cobalamin measurements yielded similar results in representative subgroups. In NPT but not MET, folate levels were inversely correlated with HOMA-IR (r = -0.239, P = .007). Folate levels did not relate to insulin sensitivity or insulin secretion in the whole cohort and in each group separately after adjustment for age, body mass index, and sex. CONCLUSIONS: Metformin does not affect circulating holoTC and folate concentrations in recent-onset type 2 diabetes, rendering monitoring of vitamin B12 and folate dispensable, at least during the first 6 months after diagnosis or initiation of metformin.

Risk of diabetes-associated diseases in subgroups of patients with recent-onset diabetes: a 5-year follow-up study.

BACKGROUND: Cluster analyses have proposed different diabetes phenotypes using age, BMI, glycaemia, homoeostasis model estimates, and islet autoantibodies. We tested whether comprehensive phenotyping validates and further characterises these clusters at diagnosis and whether relevant diabetes-related complications differ among these clusters, during 5-years of follow-up. METHODS: Patients with newly diagnosed type 1 or type 2 diabetes in the German Diabetes Study underwent comprehensive phenotyping and assessment of laboratory variables. Insulin sensitivity was assessed using hyperinsulinaemic-euglycaemic clamps, hepatocellular lipid content using magnetic resonance spectroscopy, hepatic fibrosis using non-invasive scores, and peripheral and autonomic neuropathy using functional and clinical criteria. Patients were reassessed after 5 years. The German Diabetes Study is registered with ClinicalTrials.gov, number NCT01055093, and is ongoing. FINDINGS: 1105 patients were classified at baseline into five clusters, with 386 (35%) assigned to mild age-related diabetes (MARD), 323 (29%) to mild obesity-related diabetes (MOD), 247 (22%) to severe autoimmune diabetes (SAID), 121 (11%) to severe insulin-resistant diabetes (SIRD), and 28 (3%) to severe insulin-deficient diabetes (SIDD). At 5-year follow-up, 367 patients were reassessed, 128 (35%) with MARD, 106 (29%) with MOD, 88 (24%) with SAID, 35 (10%) with SIRD, and ten (3%) with SIDD. Whole-body insulin sensitivity was lowest in patients with SIRD at baseline (mean 4·3 mg/kg per min [SD 2·0]) compared with those with SAID (8·4 mg/kg per min [3·2]; p<0·0001), MARD (7·5 mg/kg per min [2·5]; p<0·0001), MOD (6·6 mg/kg per min [2·6]; p=0·0011), and SIDD (5·5 mg/kg per min [2·4]; p=0·0035). The fasting adipose-tissue insulin resistance index at baseline was highest in patients with SIRD (median 15·6 [IQR 9·3-20·9]) and MOD (11·6 [7·4-17·9]) compared with those with MARD (6·0 [3·9-10·3]; both p<0·0001) and SAID (6·0 [3·0-9·5]; both p<0·0001). In patients with newly diagnosed diabetes, hepatocellular lipid content was highest at baseline in patients assigned to the SIRD cluster (median 19% [IQR 11-22]) compared with all other clusters (7% [2-15] for MOD, p=0·00052; 5% [2-11] for MARD, p<0·0001; 2% [0-13] for SIDD, p=0·0083; and 1% [0-3] for SAID, p<0·0001), even after adjustments for baseline medication. Accordingly, hepatic fibrosis at 5-year follow-up was more prevalent in patients with SIRD (n=7 [26%]) than in patients with SAID (n=5 [7%], p=0·0011), MARD (n=12 [12%], p=0·012), MOD (n=13 [15%], p=0·050), and SIDD (n=0 [0%], p value not available). Confirmed diabetic sensorimotor polyneuropathy was more prevalent at baseline in patients with SIDD (n=9 [36%]) compared with patients with SAID (n=10 [5%], p<0·0001), MARD (n=39 [15%], p=0·00066), MOD (n=26 [11%], p<0·0001), and SIRD (n=10 [17%], p<0·0001). INTERPRETATION: Cluster analysis can characterise cohorts with different degrees of whole-body and adipose-tissue insulin resistance. Specific diabetes clusters show different prevalence of diabetes complications at early stages of non-alcoholic fatty liver disease and diabetic neuropathy. These findings could help improve targeted prevention and treatment and enable precision medicine for diabetes and its comorbidities. FUNDING: German Diabetes Center, German Federal Ministry of Health, Ministry of Culture and Science of the state of North Rhine-Westphalia, German Federal Ministry of Education and Research, German Diabetes Association, German Center for Diabetes Research, Research Network SFB 1116 of the German Research Foundation, and Schmutzler Stiftung.

Metabolic Characteristics of Recently Diagnosed Adult-Onset Autoimmune Diabetes Mellitus.

Context and Objective: Among patients diagnosed with type 2 diabetes, autoimmune diabetes often remains undetected. Metabolic features of these patients are insufficiently characterized at present. Design, Setting, and Patients: This study compared age- and sex-matched adult (aged 41 to 62 years) humans with recent-onset diabetes: patients positive for antibodies against glutamic acid decarboxylase (GAD) and/or cytoplasmic islet-cell antigen with an insulin-free period of >6 months [antibody positive/insulin negative (ab+/ins-); previously termed latent autoimmune diabetes of adults], type 1 diabetes [antibody positive/insulin positive (ab+/ins+)], and type 2 diabetes [antibody negative/insulin negative (ab-/ins-)], as well as glucose-tolerant humans (controls) of the German Diabetes Study (n = 41/group). ß-Cell function was assessed from glucagon tests and intravenous glucose tolerance tests (IVGTTs), and insulin sensitivity was determined from hyperinsulinemic-euglycemic clamps. Results: Of the ab+/ins- patients, 33 (81%) were initially diagnosed as having type 2 diabetes. In ab+/ins-, body mass index (BMI) was higher than in ab+/ins+ (27.8 ± 5.3 kg/m2 vs 25.0 ± 3.5 kg/m2, P < 0.05), lower than in ab-/ins- (31.9 ± 5.8 kg/m2, P < 0.05), and similar to controls (29.4 ± 6.6 kg/m2). In ab+/ins-, GAD antibody titers correlated negatively with BMI (r = -0.40, P < 0.05) and with C-peptide secretion in glucagon stimulation tests (r = -0.33, P < 0.05). ß-Cell function from IVGTT was 228% higher in ab+/ins- than in ab+/ins+ but 35% lower than in ab-/ins- and 61% lower than in controls (all P < 0.05). Insulin sensitivity in ab+/ins- was comparable to ab+/ins+ and controls but 41% higher than in ab-/ins- (P < 0.05) after adjustment for BMI and fasting blood glucose or hemoglobin A1c. Conclusion: Even shortly after diagnosis, ab+/ins- patients feature partly preserved ß-cell function and chronic hyperglycemia, which possibly contributes to the observed impairment of whole-body insulin sensitivity.