Daily Endocrinology Research Analysis
Today’s most impactful endocrinology papers span prevention-focused cardiometabolic therapeutics, a definitive negative RCT in type 1 diabetes, and large-scale risk stratification in lean type 2 diabetes. GLP-1 receptor agonists reduced new-onset heart failure in high-risk populations, metformin did not improve hepatic insulin resistance in adults with type 1 diabetes, and severe underweight in type 2 diabetes was linked to higher cardiovascular risk than severe obesity.
Summary
Today’s most impactful endocrinology papers span prevention-focused cardiometabolic therapeutics, a definitive negative RCT in type 1 diabetes, and large-scale risk stratification in lean type 2 diabetes. GLP-1 receptor agonists reduced new-onset heart failure in high-risk populations, metformin did not improve hepatic insulin resistance in adults with type 1 diabetes, and severe underweight in type 2 diabetes was linked to higher cardiovascular risk than severe obesity.
Research Themes
- Cardiometabolic prevention using incretin-based therapies
- Clarifying adjunctive therapy in type 1 diabetes via rigorous RCTs
- Risk stratification in lean type 2 diabetes and implications for guidelines
Selected Articles
1. GLP-1 Receptor Agonists for the Prevention of New-Onset Heart Failure: A Systematic Review and Meta-Analysis of Placebo-Controlled Randomized Clinical Trials.
Across six placebo-controlled RCTs including 52,752 participants without baseline HF, GLP-1 receptor agonists reduced new-onset heart failure (HR 0.77) and the composite of HF events or cardiovascular death (HR 0.82). Benefits were independent of glycemic or weight effects and aligned with MACE reduction, with larger effects in established ASCVD cohorts.
Impact: This meta-analysis provides high-level evidence supporting HF prevention with GLP-1 RAs in at-risk populations, expanding their value beyond glycemic control and weight loss.
Clinical Implications: GLP-1 RAs may be prioritized for cardiometabolic risk reduction strategies to prevent incident HF in patients with type 2 diabetes or obesity, particularly those with ASCVD, independent of glycemic targets.
Key Findings
- New-onset HF was reduced with GLP-1 RAs vs placebo (HR 0.77, 95% CI 0.65–0.93).
- Composite HF events or cardiovascular death was reduced (HR 0.82, 95% CI 0.76–0.89).
- Effect was independent of HbA1c and weight changes and correlated with MACE reduction; more pronounced in ASCVD-enriched trials.
Methodological Strengths
- Meta-analysis restricted to placebo-controlled RCTs with HF-free subgroups.
- Exploration of mediation (HbA1c, weight) and heterogeneity across study characteristics.
Limitations
- HF outcomes derived from HF-free subgroups within trials; agent- and dose-specific effects not fully resolved.
- Event rates and follow-up lengths vary across RCTs; potential publication or selection biases.
Future Directions: Head-to-head comparisons and pragmatic trials to assess differential HF-preventive effects among GLP-1 agents and combinations (e.g., with SGLT2 inhibitors) and to define optimal target populations.
INTRODUCTION: Glucagon-like peptide-1 receptor agonists (GLP-1 RA) improve outcomes in heart failure (HF) with preserved ejection fraction. Whether GLP-1 RA prevent new-onset HF in Type 2 diabetes or obesity requires further investigation. METHODS: We performed an updated meta-analysis of randomized placebo-controlled trials (RCT) of treatment with GLP-1 RA in participants without HF. The hazard ratio (HR) and 95% confidence intervals (95% CI) were extracted from the group without HF in each study. The primary outcome was time to first HF event (HF hospitalization or urgent visit for HF). The correlation between the effect of GLP-1 RA on HF events and the effects on HbA1c, weight and major atherosclerotic cardiovascular events (MACE) was also investigated. We also evaluated the heterogeneity of effect according to study characteristics. RESULTS: A total of 52,752 participants without HF from six RCTs were included. Treatment with GLP-1 RA (vs. placebo) decreased the risk of new-onset HF (HR = 0.77 [95% CI 0.65-0.93], p < 0.001) and the composite of HF events or cardiovascular death (HR = 0.82 [95% CI 0.76-0.89], p < 0.001). The effect of GLP-1 RA on HF events was independent of its effects on HbA1c or weight, but was correlated with its protective effects on MACE. The effects on HF prevention were more pronounced in studies restricted to patients with atherosclerotic cardiovascular disease and in trials with higher incidence rate of HF events. CONCLUSION: Treatment with GLP-1 RA decreases the risk of new-onset HF in patients with Type 2 diabetes or obesity.
2. Effect of metformin on insulin resistance in adults with type 1 diabetes: a 26-week randomized double-blind clinical trial.
In a 26-week, double-blind RCT using gold-standard two-step clamps, metformin did not reduce hepatic insulin resistance (change in EGP) versus placebo in adults with type 1 diabetes. Safety signals (hypoglycemia, DKA) were not increased.
Impact: Provides definitive, high-quality evidence against metformin for hepatic insulin resistance in adult T1D, guiding de-implementation of a commonly considered adjunct.
Clinical Implications: Metformin should not be prescribed solely to reduce hepatic insulin resistance in adult T1D; resource allocation should prioritize therapies with proven benefit.
Key Findings
- At 26 weeks, no difference in change in endogenous glucose production vs placebo (mean difference 0.2 µmol/kgFFM/min; 95% CI −0.4 to 0.8; p=0.53).
- Adults with T1D showed hepatic, muscle, and adipose insulin resistance at baseline compared with non-diabetic controls.
- No increase in hypoglycemia or diabetic ketoacidosis with metformin.
Methodological Strengths
- Randomized, double-blind, placebo-controlled design.
- Gold-standard two-step hyperinsulinemic-euglycemic clamp quantifying hepatic insulin resistance (EGP).
Limitations
- Modest sample size (n=40 randomized; 37 completed) and 26-week duration may miss smaller effects or extrahepatic benefits.
- Single adjunctive dose (1500 mg) and adult T1D population may limit generalizability to other doses or age groups.
Future Directions: Evaluate other adjuncts (e.g., SGLT inhibitors) and mechanistic endpoints (e.g., muscle/adipose insulin sensitivity) and test different dosing or phenotypes (e.g., insulin-resistant T1D subsets).
Insulin resistance is an underrecognized cardiovascular risk factor in type 1 diabetes. The effect of metformin on insulin resistance in adults with type 1 diabetes is unknown. Forty adults with type 1 diabetes, and twenty adults without diabetes were studied in a baseline only cross-sectional study assessing insulin resistance using the two-step hyperinsulinemic-euglycemic clamp. Participants with type 1 diabetes exhibited hepatic (EGP 64% higher), muscle (glucose infusion rate [GIR] 29% lower) and adipose (higher non-esterified fatty acids [NEFA]) insulin resistance. We then conducted a parallel group randomized, placebo-controlled trial to assess the efficacy of metformin 1500 mg (n = 20) versus placebo (n = 20) in reducing insulin resistance in adults with type 1 diabetes over 26 weeks. The primary outcome was change in endogenous glucose production (EGP) during the low-dose phase of the clamp. Thirty seven of 40 adults with type 1 diabetes completed the study. At 26 weeks, there was no difference in change in EGP between metformin and placebo groups (mean difference 0.2 µmol/kg fat-free mass [FFM]/min [95%CI, -0.4 to 0.8 µmol/kgFFM/min]; p = 0.53). There was no increase in hypoglycemia or episodes of ketoacidosis in either group. These results do not support prescribing metformin to reduce hepatic insulin resistance in adults with type 1 diabetes. Australian New Zealand Clinical Trials Registry identifier, ACTRN12619001440112.
3. Underweight and cardiovascular risk in Type 2 diabetes: a Korean nationwide study.
In over 2 million adults with T2D, underweight status showed a reverse J-shaped association with CVD, with severe underweight (BMI <16 kg/m2) conferring higher risk (HR 1.49) than severe obesity (BMI ≥35 kg/m2; HR 1.14). Associations were stronger in younger and non-smoking individuals.
Impact: This very large cohort challenges obesity-centric risk paradigms in T2D by demonstrating higher CVD risk in severe underweight, highlighting a neglected high-risk phenotype with practice implications.
Clinical Implications: Guidelines should incorporate underweight severity in T2D cardiovascular risk assessment, with targeted nutrition, sarcopenia screening, and cautious therapy titration to mitigate CVD risk in lean phenotypes.
Key Findings
- Severe, moderate, and mild underweight increased CVD risk vs normal weight (HR 1.49, 1.47, and 1.19, respectively).
- CVD risk in severe underweight exceeded that of severe obesity (BMI ≥35 kg/m2; HR 1.14).
- Stronger associations observed in younger individuals and non-smokers; reverse J-shaped BMI–CVD relationship.
Methodological Strengths
- Nationwide cohort with 2,064,406 adults and robust adjustment for clinical and lifestyle covariates.
- Stratification by underweight severity and subgroup analyses enhancing external validity.
Limitations
- Residual confounding and reverse causation (illness-related weight loss) cannot be excluded.
- BMI lacks body composition detail; no direct measures of sarcopenia or frailty.
Future Directions: Prospective studies incorporating body composition, muscle function, and nutritional biomarkers to refine risk in lean T2D; interventional trials targeting sarcopenia and undernutrition.
BACKGROUND AND AIMS: With the growing prevalence of lean Type 2 diabetes mellitus (T2DM) and limited research on stratified underweight categories, this study investigated the association between underweight status and cardiovascular disease (CVD) risk in T2DM patients, focusing on the impact of underweight severity. METHODS: A nationwide cohort study analysed data from 2 064 406 adults with T2DM who underwent health examinations between 2015 and 2016, sourced from the Korean National Health Insurance Service database. Participants were classified by body mass index into underweight, normal weight, overweight, and obesity, with underweight further stratified into mild (17-18.4 kg/m2), moderate (16-16.9 kg/m2), and severe (<16 kg/m2). Primary outcomes were CVDs, including myocardial infarction and ischaemic stroke, assessed using Cox proportional hazards models adjusted for demographic, clinical, and lifestyle factors. RESULTS: During a mean follow-up of 5.7 years, 111 522 CVD events, including 55 622 MI and 62 099 ischaemic stroke events, were documented. Compared with the normal weight group, all underweight groups showed significantly higher CVD risks (adjusted hazard ratio [95% confidence interval]: 1.49 [1.28-1.73], 1.47 [1.33-1.63], and 1.19 [1.13-1.25] for severe, moderate, and mild underweight, respectively). These risks exceeded those for body mass index ≥ 35 kg/m2 (1.14 [1.08-1.22]), showing a reverse J-shaped association. Stratified analyses indicated stronger associations in younger individuals and non-smokers. CONCLUSIONS: Underweight status in T2DM patients is significantly associated with increased risk of CVDs, particularly in those severely underweight, exceeding the risks observed with obesity. These findings emphasize the need for dedicated guidelines for managing underweight T2DM patients to mitigate cardiovascular risks.