Insulin resistance--a common link between type 2 diabetes and cardiovascular disease

Evidence suggests that diabetes and cardiovascular disease (CVD) may share an underlying cause(s), a theory known as the 'common soil' hypothesis. Insulin resistance is central both to the progression from normal glucose tolerance to type 2 diabetes and to a constellation of cardiovascular risk factors known as the metabolic syndrome. These risk factors include visceral obesity and dyslipidaemia characterized by low levels of high-density lipoprotein cholesterol, hypertriglyceridaemia and raised small dense low-density lipoprotein particle levels. Changes in adipose tissue mass and metabolism may link insulin resistance and visceral obesity, a condition that is common in type 2 diabetes. Furthermore, weight reduction, increased physical activity, metformin and acarbose have been shown to reduce the development of type 2 diabetes in genetically predisposed subjects and may decrease the high cardiovascular risk of patients with diabetes. Some fatty acid derivatives can affect energy metabolism by activating peroxisome proliferator-activated receptors (PPARs), nuclear receptors that play a key role in energy homeostasis. These receptors represent an ideal therapeutic target for reducing cardiovascular risk, because they are involved in the regulation of both insulin action and lipid metabolism. In addition to lifestyle changes, PPARgamma agonists such as thiazolidinediones are frequently beneficial and have been shown to ameliorate insulin resistance, while activation of PPARalpha (e.g. by fibrates) can lead to improvements in free fatty acid oxidation and lipid profile, and a reduction in cardiovascular events. The development of agents with both PPARalpha and PPARgamma activity promises added benefits with amelioration of insulin resistance, delayed progression to and of type 2 diabetes and a reduction of CVD.     

Fixed-ratio combination of insulin degludec and liraglutide (IDegLira) improves cardiovascular risk markers in patients with type 2 diabetes uncontrolled on basal insulin

In this post hoc analysis we investigated the effects of insulin degludec/liraglutide fixed-ratio combination (IDegLira) versus comparators on cardiovascular (CV) risk markers in participants in the DUAL II (vs. insulin degludec), DUAL V (vs. insulin glargine 100 units/mL) and DUAL VII (vs. basal–bolus therapy) trials, grouped by sex, age (<65 years, ≥65 years) and diabetes duration (<10 years, ≥10 years). Treatment contrasts were in favour of IDegLira in many subgroups for changes from baseline in glycated haemoblogin (DUAL II, DUAL V), body weight (all three trials), systolic blood pressure (BP; all three trials), HDL cholesterol (DUAL VII) and LDL cholesterol (DUAL II, DUAL V). Higher heart rates were seen with IDegLira versus comparators (all three trials) plus significantly higher diastolic BP in men (DUAL V). Differences in treatment effect were seen between sexes in waist circumference (DUAL II), systolic BP (DUAL II, DUAL V) and triglycerides (DUAL VII), and between diabetes durations in LDL cholesterol (DUAL V). In conclusion, IDegLira is associated with a general improvement in CV risk markers compared with basal insulin or basal–bolus therapy after 26 weeks of treatment.     

Retinol-binding protein 4 as a plasma biomarker of renal dysfunction and cardiovascular disease in type 2 diabetes

OBJECTIVE: The retinol-binding protein 4 (RBP4) has been linked to the insulin resistance state in obesity and type 2 diabetes in animal studies. Data in humans are controversial and their relationship with organ damage in diabetic patients is lacking. We studied the association of plasma RBP4 with organ complications in type 2 diabetic patients. SETTING: Sant Joan University Hospital, Reus, Spain. SUBJECTS: 165 nonsmoker type 2 diabetic subjects according to American Diabetes Association criteria, aged 36-79 years, without proteinuria or severely decreased glomerular filtration rates (MDRD-GFR <30 mL min(-1) 1.73 m(-2)), were included in the study. MAIN OUTCOME MEASURE: Plasma RBP4 concentrations were the primary outcome variable. Statistics were performed in relation to clinical and subclinical arteriosclerosis, renal function parameters and biochemical data. RESULTS: Plasma RBP4 concentrations were positively correlated with serum creatinine levels (r = 0.322, P < 0.001) and inversely correlated with MDRD-GFR (r = -0.468, P = 0.009). Patients with moderately renal dysfunction (MDRD-GFR <60 mL min(-1) 1.73 m(-2)) had higher plasma RBP4 concentrations than those with normal to mildly decreased GFR (55.3 +/- 24.6 vs. 40.8 +/- 15.4, P <0.001). Patients in the top quartile of RBP4 concentrations had an increased adjusted odds ratio for moderately renal dysfunction compared with lower quartiles (4.68; 95% CI: 1.52-14.36, P = 0.007). The presence of microalbuminuria was not associated with RBP4. Plasma RBP4 concentrations were higher in those subjects with previous clinical arteriosclerosis than in event-free subjects (48.8 +/- 24.2 vs. 40.6 +/- 13.9, P = 0.045). The presence of retinopathy or polyneuropathy did not differ across RBP4 quartiles. CONCLUSIONS: Plasma RBP4 concentration might be a biomarker of nephropathy and cardiovascular disease in type 2 diabetic subjects.     

Impact of pre-existing type 2 diabetes with and without cardiovascular disease on patients with COVID-19

Aim

To compare adverse outcomes among COVID-19 patients with pre-existing type 2 diabetes (T2D) only, T2D and cardiovascular disease (CVD), or neither.

Methods

This retrospective cohort study used administrative claims, laboratory and mortality data from the HealthCore Integrated Research Database. Patients with COVID-19 were identified from 3 January 2020 to 31 May 2021 and stratified by the presence of T2D and CVD. Outcomes included hospitalization, intensive care unit (ICU) admission, mortality and complications following COVID-19 infection. Propensity score matching and multivariable analyses were performed.

Results

A total of 321 232 COVID-19 patients were identified (21 651 T2D + CVD, 28 184 T2D only, and 271 397 neither) with a mean (SD) follow-up of 5.4 (3.0) months. After matching, 6 967 patients were identified for each group, and residual baseline differences remained. Adjusted analyses showed that COVID-19 patients with T2D + CVD were 59% more probable to be hospitalized, 74% more probable to be admitted to the ICU, and had a 26% higher mortality risk than those with neither. COVID-19 patients with T2D only were 28% and 32% more probable to be admitted to the hospital and ICU than those with neither, respectively. Among all T2D + CVD patients, acute respiratory distress syndrome (31%) and acute kidney disease (24%) were observed.

Conclusion

Our study highlights the incrementally poorer outcomes associated with pre-existing T2D + CVD in COVID-19 patients compared with those without T2D/CVD and suggests consideration of a more optimal management approach in these patients.     

Insulin-induced weight gain and cardiovascular events in patients with type 2 diabetes. A report from the DIGAMI 2 study

Aim:  We investigated whether insulin treatment-induced weight gain was accompanied by increased cardiovascular (CV) mortality and morbidity in the second Diabetes Insulin Glucose in Acute Myocardial Infarction (DIGAMI 2) study.
Methods:  We studied the 865 patients who survived during 12 months without any change in their glucose-lowering (GL) therapy. They were divided into four subgroups according to GL treatment: group I, no pharmacological GL treatment (n = 99); group II, oral hypoglycaemic agents (n = 250); group III, new insulin treatment (n = 245) and group IV, insulin before inclusion continued during the first year of follow up (n = 271).
Results:  Patients who started on insulin (group III) experienced an average body weight increase of 2.3 (1.5–3.2) kg during the first year of treatment, whereas weight remained unchanged in groups I, II and IV. The incidence of non-fatal reinfarction was higher in group III compared with the other groups (hazard ratio (HR) = 2.5, p   = 0.011) and CV mortality was higher in group IV (HR = 2.4, p   = 0.003). When the subjects were grouped in quartiles according to maximal body weight increase, those in the lowest quartile experienced the highest CV mortality. Each kilogram increase in weight reduced the risk for CV death with 6%. The incidence of reinfarction did not differ between quartiles.
Conclusions:  Initiation of insulin treatment after myocardial infarction was associated with a significant increase in weight and incidence of reinfarction. The increase in weight did, however, not explain the increased rate of reinfarction.     

Cardiovascular disease in type 2 diabetes: challenge for treatment and prevention

Type 2 diabetes increases the risk of cardiovascular disease (CVD) two- to fourfold compared with the risk in non-diabetic subjects. Although type 2 diabetes is associated with a clustering of risk factors (small, dense low-density lipoprotein [LDL] particles, low high-density lipoprotein [HDL] cholesterol, high triglycerides, elevated blood pressure, obesity, central obesity, hyperinsulinaemia, hyperglycaemia, etc.), the cause for an excess risk of CVD remains unknown. Recent drug treatment trials have indicated that the lowering of total and LDL cholesterol and blood pressure is similarly beneficial in diabetic and non-diabetic subjects. The treatment of hyperglycaemia reduces micro- and macrovascular complications in type 2 diabetic patients. Beta-blocking agents, angiotensin-converting enzyme inhibitors, aspirin, and thrombolytic therapy are also effective in the treatment of CVD amongst diabetic patients.     

Insulin sensitivity at diagnosis of Type 2 diabetes is not associated with subsequent cardiovascular disease (UKPDS 67).

AIMS: Insulin resistance is common in Type 2 diabetes which, in turn, is associated with a markedly increased risk of cardiovascular disease. Whether insulin sensitivity measured after diagnosis of diabetes is associated with incident cardiovascular disease was evaluated in this prospective study. METHODS: Three thousand five hundred and eighty-two subjects with newly diagnosed diabetes, recruited to the UK Prospective Diabetes Study (UKPDS), free of cardiovascular disease, and with complete information on insulin sensitivity and potential confounders, were followed prospectively to the first occurrence of (i) fatal or non-fatal myocardial infarction, MI (ii) fatal or non-fatal stroke, and (iii) coronary heart disease, CHD (fatal or non-fatal MI, sudden death or ischaemic heart disease). Insulin sensitivity was measured by Homeostatic Model Assessment (HOMA). RESULTS: Insulin sensitivity as measured by HOMA was not associated with subsequent MI, stroke, or CHD in univariate or multivariate models controlling for age, sex, ethnicity, HbA(1c), body mass index, plasma triglycerides, cholesterol and smoking. The hazard ratio associated with a doubling of insulin sensitivity with fatal or non-fatal MI in a multivariate model was 0.92 (95% confidence interval, CI, 0.80-1.05). These results were not changed by the exclusion of overweight patients randomized to metformin. DISCUSSION: Estimation of insulin sensitivity provides no additional useful information with respect to the risk of the first occurrence of cardiovascular disease in patients with newly diagnosed Type 2 diabetes. Among patients with Type 2 diabetes, insulin resistance is not a risk factor for cardiovascular disease.     

Increased 24h mean insulin-like growth factor binding protein-3 proteolytic activity in pubertal type 1 diabetic boys

Hyperglycaemia and increased variability of blood glucose in pubertal children with type 1 diabetes may be related to increased growth hormone (GH) secretion and insulin resistance. The role of changes in insulin-like growth factor-I (IGF-I) bioavailability for the glycaemic control in these patients has not been completely elucidated. In particular, the possible role of increased IGF binding protein-3 (IGFBP-3) proteolysis reported in other insulin resistant states awaits further characterization. The aims of this study were to assess if hyperglycaemia in children with type 1 diabetes was associated with changes in free dissociable IGF-I (fdIGF-I) and IGF binding protein-3 protease activity (IGFBP-3-PA) and if increased insulin resistance during puberty was associated with changes in IGFBP-3-PA in healthy and diabetic children. In diabetic boys in the period of maximal linear growth (Tanner stage 3, n = 5), the mean level and the variability of IGFBP-3-PA, determined every second hour throughout 24 h, were significantly higher both compared to postpubertal diabetic boys (n = 6; P = 0.003 and P = 0.001, respectively), and to age matched healthy boys (n = 4; P = 0.006 and P < 0.001 respectively). This activation of IGFBP-3-PA was most prominent during the day time.The mean 24 h blood glucose level (determined hourly) was the only parameter studied that significantly predicted the changes in mean 24 h IGFBP-3-PA in the diabetes group. The mean 24 h concentrations of fdIGF-I were decreased in the diabetic boys compared to the healthy controls but statistical significance was only achieved in Tanner Stage 5 (p = 0.03). We speculate that the elevated levels of IGFBP-3-PA in Tanner 3 diabetic boys are related to deteriorated glucose homeostasis and that it may be a compensatory mechanism to attenuate the decrease in fdIGF-I in order to partly restore insulin sensitivity and glycemic control.     

Effects of oral semaglutide on cardiovascular outcomes in individuals with type 2 diabetes and established atherosclerotic cardiovascular disease and/or chronic kidney disease: Design and baseline characteristics of SOUL,a randomized trial

Aim

To describe the design of the SOUL trial (Semaglutide cardiOvascular oUtcomes triaL) and the baseline clinical data of its participants.

Materials and methods

In SOUL, the effects of oral semaglutide, the first oral glucagon-like peptide-1 receptor agonist, on the risk of cardiovascular (CV) events in individuals with type 2 diabetes and established atherosclerotic CV disease (ASCVD) and/or chronic kidney disease (CKD) will be assessed. SOUL is a randomized, double-blind, parallel-group, placebo-controlled CV outcomes trial comparing oral semaglutide (14 mg once daily) with placebo, both in addition to standard of care, in individuals aged ≥50 years with type 2 diabetes and evidence of ASCVD (coronary artery disease [CAD], cerebrovascular disease, symptomatic peripheral arterial disease [PAD]) and/or CKD (estimated glomerular filtration rate <60 mL/min/1.73 m²). The primary outcome is time from randomization to first occurrence of a major adverse CV event (MACE; a composite of CV death, nonfatal myocardial infarction or nonfatal stroke). This event-driven trial will continue until 1225 first adjudication-confirmed MACEs have occurred. Enrolment has been completed.

Results

Overall, 9650 participants were enrolled between June 17, 2019 and March 24, 2021 (men 71.1%, White ethnicity 68.9%, mean age 66.1 years, diabetes duration 15.4 years, body mass index 31.1 kg/m², glycated haemoglobin 63.5 mmol/mol [8.0%]). The most frequently used antihyperglycaemic medications at baseline were metformin (75.7%), insulin and insulin analogues (50.5%), sulphonylureas (29.1%), sodium-glucose cotransporter-2 inhibitors (26.7%) and dipeptidyl peptidase-4 inhibitors (23.0%). At randomization, 70.7% of participants had CAD, 42.3% had CKD, 21.1% had cerebrovascular disease and 15.7% had symptomatic PAD (categories not mutually exclusive). Prevalent heart failure was reported in 23.0% of participants.

Conclusion

SOUL will provide evidence regarding the CV effects of oral semaglutide in individuals with type 2 diabetes and established ASCVD and/or CKD.