Association between severe hypoglycemia, adverse macrovascular events, and inflammation in the Edinburgh Type 2 Diabetes Study

Effects of equivalent sympathetic activation during hypoglycemia on endothelial function and pro-atherothrombotic balance in healthy individuals and obese standard treated type 2 diabetes

OBJECTIVE

Recent studies in type 2 diabetes have reported an association between hypoglycemia and severe cardiovascular adverse events, which are relatively increased in standard versus intensively treated individuals. The aim of this study was to determine the effects of equivalent sympathetic nervous system (SNS) activity during moderate hypoglycemia on in-vivo endothelial function, pro-inflammatory, pro-atherothrombotic, and pro-coagulant responses in healthy and standard treated type 2 diabetes individuals.

RESEARCH DESIGN AND METHODS

Eleven type 2 diabetes and 16 healthy individuals participated in single 2day studies. Day 1 involved a 2h hyperinsulinemic/euglycemic clamp and day 2, a 2h hyperinsulinemic/hypoglycemic clamp of 3.2±1mmol/L in type 2 diabetes and (2.9±0.1mmol/L) in healthy individuals.

RESULTS

ICAM-1, VCAM-1, P-selectin, PAI-1, VEGF and endothelin-1 (ET-1) fell during hyperinsulinemic euglycemia but increased during hypoglycemia in type 2 diabetes and healthy individuals. Epinephrine and norepinephrine levels were equivalent during hypoglycemia in type 2 DM and healthy individuals. However, despite similar SNS drive but milder and hypoglycemia there were greater ICAM-1, VCAM-1, PAI-1, VEGF and ET-1 responses in the type 2 diabetes group. Endogenous and exogenous nitric oxide mediated arterial vasodilation were also impaired only during hypoglycemia in type 2 diabetes.

CONCLUSION

We conclude that, milder hypoglycemia but equivalent SNS activation results in more diffuse endothelial dysfunction and a greater pro-inflammatory, pro-atherothrombotic and pro-coagulant state in standard treated type 2 diabetes as compared to healthy individuals.

[Management of hyperglycemic/diabetic patient during and in the immediate follow-up of an acute coronary syndrome]

Two thirds of the patients hospitalized for an acute coronary syndrome (ACS) show disorders of glucose metabolism (diabetes, impaired fasting glucose, impaired glucose intolerance). Every patient hospitalized for an ACS whose HbA1c is equal or above 6.5% must be considered as diabetic. Each patient hospitalized for an ACS whose HbA1c is less than 6.5% should have measurement of plasma glucose fasting and after an oral glucose load between the 7th and the 28th day following the ACS in order to detect a disorder of glucose metabolism. During the hospitalization in cardiac intensive care unit, a treatment with insulin will be started when plasma glucose is≥1.80g/L (10.0mmol/L). In a patient with previously known diabetes, a treatment with insulin will also be started when preprandial plasma glucose is 1.40g/L (7.8mmol/L). Insulin treatment in cardiac intensive care unit will be performed by continuous IV infusion of insulin including bolus for meals. Insulin dosage will be determined according to the capillary glucose monitoring. After the hospitalization in cardiac intensive care unit, it is often possible to stop insulin treatment, which may be replaced by other antidiabetic treatments. The choice of the optimal antidiabetic treatment depends on the metabolic profile of the patient (insulin-resistance, insulin deficiency). This choice is not always easy and referral to an endocrinologist/diabetolgist may be needed. Because of the increased cardiovascular mortality associated with hypoglycemias, the long-term use of insulin or insulin-secretory agents (sulfonylureas, glinides) must be limited. During and in the immediate follow-up of an ACS, referral to an endocrinologist/diabetologist is recommended in case of diagnosis of diabetes, when HbA1c≥8%, when long-term treatment with insulin has been initiated and in case of frequent or severe hypoglycemias.

Comparative effects of acute hypoglycemia and hyperglycemia on pro-atherothrombotic biomarkers and endothelial function in non-diabetic humans

BACKGROUND

The comparative effects of acute moderate hyperglycemia and hypoglycemia on in vivo endothelial function together with pro-inflammatory and pro-atherothrombotic responses in healthy individuals have not been determined.

METHODS

To investigate this question, 45 healthy subjects were compared during glucose clamp studies consisting of euinsulinemic hyperglycemia and hyperinsulinemic hyperglycemia (plasma glucose 11.1mmol/L, both with pancreatic clamps) and hyperinsulinemic euglycemia and hyperinsulinemic hypoglycemia (plasma glucose 5.1 and 2.9mmol/L, respectively). Two-dimensional Doppler ultrasound was used to determine brachial artery endothelial function.

RESULTS

Insulin levels during euinsulinemia hyperglycemia were 194±23 and (850±49-988±114) pmol/L during all hyperinsulinemic protocols. Responses of VCAM-1, ICAM-1, E-selectin, P-selectin, PAI-1, and IL-6 were increased (p<0.05-0.0001) during euinsulinemic hyperglycemia or hypoglycemia as compared to hyperinsulinemic euglycemia or hyperinsulinemic hyperglycemia. PAI-1 was increased (p<0.04) during hypoglycemia as compared to euinsulinemic hyperglycemia, and TNF-α responses were also increased during hypoglycemia as compared to hyperinsulinemic euglycemia or hyperinsulinemic hyperglycemia (p<0.05). In vivo endothelial function was similarly blunted by acute moderate hyperglycemia or hypoglycemia.

CONCLUSION

In summary, acute moderate hypoglycemia and euinsulinemic hyperglycemia can result in similar endothelial dysfunction and pro-atherothrombotic responses. Fibrinolytic balance was reduced by a greater extent by hypoglycemia as compared to moderate hyperglycemia. Acutely, hyperinsulinemia can prevent the acute pro-atherothrombotic and pro-inflammatory effects of moderate hyperglycemia but not hypoglycemia.

Hypoglycemia and Cardiovascular Risk: Is There a Major Link?

Severe hypoglycemia is recognized to be one of the strongest predictors of macrovascular events, adverse clinical outcomes, and mortality in patients with type 2 diabetes. However, it is uncertain whether a direct pathophysiological link exists or whether hypoglycemia is primarily a marker of vulnerability to these events. Large clinical trials have reported an increased hazard ratio for all-cause mortality and cardiovascular events in patients with type 2 diabetes and severe hypoglycemia, but such an association has not been demonstrated in prospective trials of people with type 1 diabetes. Several cardiovascular effects occur during hypoglycemia either as a result of low blood glucose levels per se or through activation of the sympathoadrenal response: hemodynamic changes with an increase in cardiac work load and potential attenuation of myocardial perfusion, electrophysiological changes that may be arrhythmogenic, induction of a prothrombotic state, and release of inflammatory markers. Although the potential for a causal relationship has been demonstrated in mechanistic studies, the evidence from large prospective studies that hypoglycemia is a major causal contributor to cardiovascular events is limited to date. Other preexisting cardiovascular risk factors in addition to hypoglycemia may be the major link to the final cardiovascular event, but a low blood glucose level can trigger these events in patients with a high cardiovascular risk.

Diabetes for Cardiologists: Practical Issues in Diagnosis and Management

Diabetes mellitus (DM), a chronic metabolic disease characterized by hyperglycemia, is a profound cardiovascular (CV) risk factor. It compounds the effects of all other risk factors, leads to premature micro- and macrovascular disease, facilitates development of heart failure, worsens the clinical course of all CV diseases, and shortens life expectancy. Established DM, unrecognized DM, and dysglycemia that may progress to DM are all commonly present at the time of presentation of overt CV disease. Thus, CV specialists and trainees frequently treat patients with dysglycemia. The traditional and proven role of cardiologists in reducing the risk of macrovascular events in this population is through aggressive lipid and blood pressure treatment. However, a more proactive role in the detection and management of DM is likely to become increasingly important as the prevalence continues to increase and therapies continue to improve. The latter include antihyperglycemic therapies with proven cardiovascular safety profiles and CV event reduction properties not yet fully elucidated and not necessarily related to glycemic control. Accordingly, the purpose of this article is to (1) expand the interest of cardiologists in earlier stages of the natural history of DM, when prevention or early detection might help achieve greatest benefit; (2) highlight principles of optimal glycemic management, with an emphasis on add-on choices showing promising reduction of CV events and lacking CV adverse effects; and (3) encourage cardiologists to become proactive partners in the multidisciplinary care needed to ensure optimal lifelong vascular health in patients with, or who are at risk of, DM.

Insulin glargine versus insulin degludec in patients failing on oral therapy in type 2 diabetes: A retrospective real world comparative data from India

OBJECTIVE

To compare the changes in various glycemic parameters in insulin-naïve type 2 diabetes mellitus (DM) patients who were initiated on insulin glargine or insulin degludec in a real world setting.

METHODS

Retrospective data were analyzed in consecutive type 2 DM patients in a real world setting, who failed oral therapy (at least 2 oral anti-diabetic drugs) and were initiated with either insulin glargine or insulin degludec. The parameters assessed were the changes in HbA1c, fasting plasma glucose, body weight, dose of Insulin and the total number of patient reported hypoglycemic episodes up to 6 months after initiation.

RESULT

At baseline, insulin glargine and insulin degludec groups were similar in terms of gender, age, weight, HbA1c and duration of diabetes. After 6 months follow up the change in HbA1c (-1.09 versus -1.45 P=0.124), change in FPG (-72.81mg/dl [-4mmol/L] versus -75.88mg/dl [-4.2mmol/L] P=0.755), and the change in body weight (+1.65 versus +0.85 P=0.082) were similar in glargine and degludec groups, respectively. Patients in insulin degludec group experienced significantly lesser patient reported hypoglycemic episodes (12 versus 40) and required significantly lesser dose (25.68Units versus 18.61Units per day; P=0.002) compared to insulin glargine. 41% of the patients reached HbA1C target of ≤7% with insulin glargine compared to 69% with insulin degludec within the specified time period.

CONCLUSION

Results from this real world analysis suggest that among type 2 DM patients who were initiated on insulin degludec as compared to insulin glargine may be associated with significantly lesser patient reported hypoglycemic episodes and lesser dose of insulin while achieving similar glycemic control. This study is however limited by the retrospective nature of the data collection.

Severe Hypoglycemia and Cardiovascular or All-Cause Mortality in Patients with Type 2 Diabetes

BACKGROUND

We investigated the association between severe hypoglycemia (SH) and the risk of cardiovascular (CV) or all-cause mortality in patients with type 2 diabetes.

METHODS

The study included 1,260 patients aged 25 to 75 years with type 2 diabetes from the Vincent Type 2 Diabetes Resgistry (VDR), who consecutively enrolled (n=1,260) from January 2000 to December 2010 and were followed up until May 2015 with a median follow-up time of 10.4 years. Primary outcomes were death from any cause or CV death. We investigated the association between the CV or all-cause mortality and various covariates using Cox proportional hazards regression analysis.

RESULTS

Among the 906 participants (71.9%) who completed follow-up, 85 patients (9.4%) had at least one episode of SH, and 86 patients (9.5%) died (9.1 per 1,000 patient-years). Patients who had died were older, had a longer duration of diabetes and hypertension, received more insulin, and had more diabetic microvascular complications at baseline, as compared with surviving patients. The experience of SH was significantly associated with an increased risk of all-cause mortality (hazard ratio [HR], 2.64; 95% confidence interval [CI], 1.39 to 5.02; P=0.003) and CV mortality (HR, 6.34; 95% CI, 2.02 to 19.87; P=0.002) after adjusting for sex, age, diabetic duration, hypertension, mean glycosylated hemoglobin levels, diabetic nephropathy, lipid profiles, and insulin use.

CONCLUSION

We found a strong association between SH and increased risk of all-cause and CV mortality in patients with type 2 diabetes.

Clinical implications of oxidative stress and potential role of natural antioxidants in diabetic vascular complications

AIMS

The possible link between hyperglycaemia-induced oxidative stress (OxS) and diabetic complications is suggested by many in vitro studies. However, not much attention has been paid to the clinical evidence supporting this hypothesis, as well as to their possible therapeutic implications.

DATA SYNTHESIS

Some prospective studies show a direct correlation between an increase in OxS biomarkers and the appearance of diabetes complications. This is consistent with the evidence that any acute increase of glycaemia, particularly post-prandial, and hypoglycaemia causes endothelial dysfunction and inflammation, through the generation of an OxS. However, the detection of free radicals is difficult as they are highly reactive molecules with a short half-life. Instead, the metabolites of OxS are measured. Interventional trials with supplemented antioxidants have failed to show any beneficial effects. Conversely, natural foods show very promising results.

CONCLUSIONS

The "new antioxidant" approach includes the possibility of controlling free radical production and increasing intracellular antioxidant defence, a concept different from the old one, when antioxidant activities implied scavenging the free radicals already produced. A synergistic action in this respect could convincingly be obtained with a balanced 'Mediterranean Diet' (MedD) type. Early intensive glucose control is still the best strategy to avoid OxS and its associated diabetes complications.

Association Between Severe Hypoglycemia and Cardiovascular Disease Risk in Japanese Patients With Type 2 Diabetes

Background

It remains unclear whether severe hypoglycemia is associated with cardiovascular disease (CVD) in Asian populations with type 2 diabetes (T2D). Furthermore, no study in Japan, where the prescription patterns differ from those in other countries, has examined this association.

Methods and Results

We retrospectively included 58 223 patients (18–74 years old) with T2D. First, we examined the potential predictors of severe hypoglycemia. Then, we investigated the association between severe hypoglycemia and CVD risk. Finally, we performed an updated systematic review and meta‐analysis to incorporate our findings and recently published studies into the previous systematic review and meta‐analysis. During 134 597 person‐years from cumulative observation periods, 128 persons experienced severe hypoglycemia and 550 developed CVD events. In a multivariate Cox proportional hazard model, severe hypoglycemia was strongly and positively associated with the risk of CVD (multivariate‐adjusted adjusted hazard ratio, 3.39; 95% CI, 1.25–9.18). In a propensity score–matched cohort that had similar baseline characteristics for patients with severe hypoglycemia and those without, severe hypoglycemia was more strongly associated with the risk of CVD. An updated systematic review and meta‐analysis that included 10 studies found that severe hypoglycemia was associated with an ≈2‐fold increased risk of CVD (pooled relative risk, 1.91; 95% CI, 1.69–2.15).

Conclusions

Our results suggest that severe hypoglycemia is strongly associated with an increased risk of CVD in Japanese patients with T2D, further supporting the notion that avoiding severe hypoglycemia may be important in preventing CVD in this patient population.

Risk of and risk factors for hypoglycemia and associated arrhythmias in patients with type 2 diabetes and cardiovascular disease: a cohort study under real-world conditions

AIMS

Severe hypoglycemia is one of the strongest predictors of adverse clinical outcomes in patients with type 2 diabetes. Our study addressed the question whether there is a relationship between hypoglycemic events (HE) and severe cardiac arrhythmias in type 2 diabetic patients with established clinical risk factors under real-world conditions.

METHODS

We included 94 patients with type 2 diabetes and documented cardiovascular disease, in which interstitial glucose values and Holter ECG were recorded for 5 days in parallel. Patients received a stable treatment with insulin and/or sulfonylurea and were instructed to record symptoms of hypoglycemia or arrhythmias.

RESULTS

Continuous glucose monitoring revealed 54 HE (interstitial glucose <3.1 mmol/l) in a total of 26 patients. Patients perceived only 39 % of HE during the day and 11 % of HE during the night. Patients with HE had a significantly higher number of severe ventricular arrhythmias [ventricular tachycardia (VT) 32.8 ± 60 vs. 0.9 ± 4.2, p = 0.019], and multivariate regression analysis revealed the duration of severe HE and TSH level as independent predictors of the occurrence of a VT.

CONCLUSIONS

In conclusion, our study suggests that hypoglycemia might be able to trigger at least under certain circumstances, such as low TSH, ventricular arrhythmias under real-world conditions. The large number of unrecognized HE and VT in vulnerable patients treated with insulin or sulfonylurea should encourage the practitioner to focus on stable glucose control and to search for silent HE.

Glycemic Variability and Diabetes Complications: Does It Matter? Of Course It Does!

There is no argument that improving mean levels of glycemic control as judged by assays for glycated hemoglobin (HbA(1c)) reduces the risks of microvascular complications and cardiovascular disease events in patients with type 1 and type 2 diabetes. However, observations in some trials have suggested that targeting HbA(1c) to suggested targets may not always result in improved outcomes for people with long-standing type 2 diabetes. The reasons why the glycemic control strategies that primarily use HbA(1c) in these studies did not have predicted outcomes are not clear. Thus, controversy remains as to whether there are glycemic metrics beyond HbA(1c) that can be defined as effective measures that can be used in addition to HbA(1c) to help in assessing the risk of an individual developing diabetes complications. In this regard, the concept of "glycemic variability" (GV) is one metric that has attracted a lot of attention. GV can be simply defined as the degree to which a patient's blood glucose level fluctuates between high (peaks) and low (nadir) levels. The best and most precise way to assess GV is also one that is still debated. Thus, while there is universal agreement that HbA(1c) is the current gold standard for the primary clinical target, there is no consensus as to whether other proposed glycemic metrics hold promise to provide additional clinical data or whether there should be additional targets beyond HbA(1c). Therefore, given the current controversy, we provide a Point-Counterpoint debate on this issue. In the point narrative below, Dr. Hirsch provides his argument that fluctuations in blood glucose as assessed by GV metrics are deleterious and control of GV should be a primary treatment target. In the following counterpoint narrative, Dr. Bergenstal argues that there are better markers to assess the risk of diabetes than GV and provides his consideration of other concepts.