CVOT Summit Report 2023: new cardiovascular, kidney, and metabolic outcomes.

The 9th Cardiovascular Outcome Trial (CVOT) Summit: Congress on Cardiovascular, Kidney, and Metabolic Outcomes was held virtually on November 30-December 1, 2023. This reference congress served as a platform for in-depth discussions and exchange on recently completed outcomes trials including dapagliflozin (DAPA-MI), semaglutide (SELECT and STEP-HFpEF) and bempedoic acid (CLEAR Outcomes), and the advances they represent in reducing the risk of major adverse cardiovascular events (MACE), improving metabolic outcomes, and treating obesity-related heart failure with preserved ejection fraction (HFpEF). A broad audience of endocrinologists, diabetologists, cardiologists, nephrologists and primary care physicians participated in online discussions on guideline updates for the management of cardiovascular disease (CVD) in diabetes, heart failure (HF) and chronic kidney disease (CKD); advances in the management of type 1 diabetes (T1D) and its comorbidities; advances in the management of CKD with SGLT2 inhibitors and non-steroidal mineralocorticoid receptor antagonists (nsMRAs); and advances in the treatment of obesity with GLP-1 and dual GIP/GLP-1 receptor agonists. The association of diabetes and obesity with nonalcoholic steatohepatitis (NASH; metabolic dysfunction-associated steatohepatitis, MASH) and cancer and possible treatments for these complications were also explored. It is generally assumed that treatment of chronic diseases is equally effective for all patients. However, as discussed at the Summit, this assumption may not be true. Therefore, it is important to enroll patients from diverse racial and ethnic groups in clinical trials and to analyze patient-reported outcomes to assess treatment efficacy, and to develop innovative approaches to tailor medications to those who benefit most with minimal side effects. Other keys to a successful management of diabetes and comorbidities, including dementia, entail the use of continuous glucose monitoring (CGM) technology and the implementation of appropriate patient-physician communication strategies. The 10th Cardiovascular Outcome Trial Summit will be held virtually on December 5-6, 2024 ( http://www.cvot.org ).

Data from network meta-analyses can inform clinical practice guidelines and decision-making in diabetes management: perspectives of the taskforce of the guideline workshop.

In recent years, several novel agents have become available to treat individuals with type 2 diabetes (T2D), such as sodium-glucose cotransporter-2 inhibitors (SGLT-2i), tirzepatide, which is a dual glucose-dependent insulinotropic polypeptide receptor agonist (GIP RA)/glucagon-like peptide-1 receptor agonist (GLP-1 RA), and finerenone, a non-steroidal mineralocorticoid receptor antagonist (MRA) that confers significant renal and cardiovascular benefits in individuals with (CKD). New medications have the potential to improve the lives of individuals with diabetes. However, clinicians are challenged to understand the benefits and potential risks associated with these new and emerging treatment options. In this article, we discuss how use of network meta-analyses (NMA) can fill this need.

Benefits and harms of drug treatment for type 2 diabetes: systematic review and network meta-analysis of randomised controlled trials.

OBJECTIVE: To compare the benefits and harms of drug treatments for adults with type 2 diabetes, adding non-steroidal mineralocorticoid receptor antagonists (including finerenone) and tirzepatide (a dual glucose dependent insulinotropic polypeptide (GIP)/glucagon-like peptide-1 (GLP-1) receptor agonist) to previously existing treatment options. DESIGN: Systematic review and network meta-analysis. DATA SOURCES: Ovid Medline, Embase, and Cochrane Central up to 14 October 2022. ELIGIBILITY CRITERIA FOR SELECTING STUDIES: Eligible randomised controlled trials compared drugs of interest in adults with type 2 diabetes. Eligible trials had a follow-up of 24 weeks or longer. Trials systematically comparing combinations of more than one drug treatment class with no drug, subgroup analyses of randomised controlled trials, and non-English language studies were deemed ineligible. Certainty of evidence was assessed following the GRADE (grading of recommendations, assessment, development and evaluation) approach. RESULTS: The analysis identified 816 trials with 471 038 patients, together evaluating 13 different drug classes; all subsequent estimates refer to the comparison with standard treatments. Sodium glucose cotransporter-2 (SGLT-2) inhibitors (odds ratio 0.88, 95% confidence interval 0.83 to 0.94; high certainty) and GLP-1 receptor agonists (0.88, 0.82 to 0.93; high certainty) reduce all cause death; non-steroidal mineralocorticoid receptor antagonists, so far tested only with finerenone in patients with chronic kidney disease, probably reduce mortality (0.89, 0.79 to 1.00; moderate certainty); other drugs may not. The study confirmed the benefits of SGLT-2 inhibitors and GLP-1 receptor agonists in reducing cardiovascular death, non-fatal myocardial infarction, admission to hospital for heart failure, and end stage kidney disease. Finerenone probably reduces admissions to hospital for heart failure and end stage kidney disease, and possibly cardiovascular death. Only GLP-1 receptor agonists reduce non-fatal stroke; SGLT-2 inhibitors are superior to other drugs in reducing end stage kidney disease. GLP-1 receptor agonists and probably SGLT-2 inhibitors and tirzepatide improve quality of life. Reported harms were largely specific to drug class (eg, genital infections with SGLT-2 inhibitors, severe gastrointestinal adverse events with tirzepatide and GLP-1 receptor agonists, hyperkalaemia leading to admission to hospital with finerenone). Tirzepatide probably results in the largest reduction in body weight (mean difference -8.57 kg; moderate certainty). Basal insulin (mean difference 2.15 kg; moderate certainty) and thiazolidinediones (mean difference 2.81 kg; moderate certainty) probably result in the largest increases in body weight. Absolute benefits of SGLT-2 inhibitors, GLP-1 receptor agonists, and finerenone vary in people with type 2 diabetes, depending on baseline risks for cardiovascular and kidney outcomes (https://matchit.magicevidence.org/230125dist-diabetes). CONCLUSIONS: This network meta-analysis extends knowledge beyond confirming the substantial benefits with the use of SGLT-2 inhibitors and GLP-1 receptor agonists in reducing adverse cardiovascular and kidney outcomes and death by adding information on finerenone and tirzepatide. These findings highlight the need for continuous assessment of scientific progress to introduce cutting edge updates in clinical practice guidelines for people with type 2 diabetes. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42022325948.

CVOT Summit 2022 Report: new cardiovascular, kidney, and glycemic outcomes.

The 8th Cardiovascular Outcome Trial (CVOT) Summit on Cardiovascular, Kidney, and Glycemic Outcomes was held virtually on November 10-12, 2022. Following the tradition of previous summits, this reference congress served as a platform for in-depth discussion and exchange on recently completed outcomes trials as well as key trials important to the cardiovascular (CV) field. This year's focus was on the results of the DELIVER, EMPA-KIDNEY and SURMOUNT-1 trials and their implications for the treatment of heart failure (HF) and chronic kidney disease (CKD) with sodium-glucose cotransporter-2 (SGLT2) inhibitors and obesity with glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptor agonists. A broad audience of primary care physicians, diabetologists, endocrinologists, cardiologists, and nephrologists participated online in discussions on new consensus recommendations and guideline updates on type 2 diabetes (T2D) and CKD management, overcoming clinical inertia, glycemic markers, continuous glucose monitoring (CGM), novel insulin preparations, combination therapy, and reclassification of T2D. The impact of cardiovascular outcomes on the design of non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) trials, as well as the impact of real-world evidence (RWE) studies on the confirmation of CVOT outcomes and clinical trial design, were also intensively discussed. The 9th Cardiovascular Outcome Trial Summit will be held virtually on November 23-24, 2023 ( http://www.cvot.org ).

Heart failure in type 2 diabetes: current perspectives on screening, diagnosis and management.

Type 2 diabetes is one of the most relevant risk factors for heart failure, the prevalence of which is increasing worldwide. The aim of the review is to highlight the current perspectives of the pathophysiology of heart failure as it pertains to type 2 diabetes. This review summarizes the proposed mechanistic bases, explaining the myocardial damage induced by diabetes-related stressors and other risk factors, i.e., cardiomyopathy in type 2 diabetes. We highlight the complex pathology of individuals with type 2 diabetes, including the relationship with chronic kidney disease, metabolic alterations, and heart failure. We also discuss the current criteria used for heart failure diagnosis and the gold standard screening tools for individuals with type 2 diabetes. Currently approved pharmacological therapies with primary use in type 2 diabetes and heart failure, and the treatment-guiding role of NT-proBNP are also presented. Finally, the influence of the presence of type 2 diabetes as well as heart failure on COVID-19 severity is briefly discussed.

Causes of Death in a Contemporary Cohort of Patients With Type 2 Diabetes and Atherosclerotic Cardiovascular Disease: Insights From the TECOS Trial.

OBJECTIVE: We evaluated the specific causes of death and their associated risk factors in a contemporary cohort of patients with type 2 diabetes and atherosclerotic cardiovascular disease (ASCVD). RESEARCH DESIGN AND METHODS: We used data from the Trial Evaluating Cardiovascular Outcomes with Sitagliptin (TECOS) study (n = 14,671), a cardiovascular (CV) safety trial adding sitagliptin versus placebo to usual care in patients with type 2 diabetes and ASCVD (median follow-up 3 years). An independent committee blinded to treatment assignment adjudicated each cause of death. Cox proportional hazards models were used to identify risk factors associated with each outcome. RESULTS: A total of 1,084 deaths were adjudicated as the following: 530 CV (1.2/100 patient-years [PY], 49% of deaths), 338 non-CV (0.77/100 PY, 31% of deaths), and 216 unknown (0.49/100 PY, 20% of deaths). The most common CV death was sudden death (n = 145, 27% of CV death) followed by acute myocardial infarction (MI)/stroke (n = 113 [MI n = 48, stroke n = 65], 21% of CV death) and heart failure (HF) (n = 63, 12% of CV death). The most common non-CV death was malignancy (n = 154, 46% of non-CV death). The risk of specific CV death subcategories was lower among patients with no baseline history of HF, including sudden death (hazard ratio [HR] 0.4; P = 0.0036), MI/stroke death (HR 0.47; P = 0.049), and HF death (HR 0.29; P = 0.0057). CONCLUSIONS: In this analysis of a contemporary cohort of patients with diabetes and ASCVD, sudden death was the most common subcategory of CV death. HF prevention may represent an avenue to reduce the risk of specific CV death subcategories.

Assessing the Safety of Sitagliptin in Older Participants in the Trial Evaluating Cardiovascular Outcomes with Sitagliptin (TECOS).

OBJECTIVE: Limited data exist regarding safety and efficacy of antihyperglycemic drugs in older patients with type 2 diabetes. The Trial Evaluating Cardiovascular Outcomes with Sitagliptin (TECOS) was a randomized, double-blind, placebo-controlled trial assessing the impact of sitagliptin on a primary composite outcome of cardiovascular death, nonfatal stroke, nonfatal myocardial infarction, or unstable angina hospitalizations in patients with type 2 diabetes (HbA1c ≥6.5% [48 mmol/mol] and ≤8.0% [64 mmol/mol]) and cardiovascular disease. We analyzed baseline characteristics and clinical outcomes for TECOS participants aged ≥75 years. RESEARCH DESIGN AND METHODS: Clinical and safety event summaries are presented for older versus younger participants and for the treatment groups within the older cohort. RESULTS: Of 14,351 participants with age recorded, 2,004 (14%) were ≥75 years old (mean age 78.3 years [SD 3.1]), with 68% men and type 2 diabetes duration median 12.0 years (IQR 7, 21). During 2.9 years median follow-up, older participants had higher rates of the primary outcome (6.46 vs. 3.67 events per 100 person-years; hazard ratio 1.72 [95% CI 1.52-1.94]), death (2.52 [2.20-2.89]), severe hypoglycemia (1.53 [1.15-2.03]), and fractures (1.84 [1.44-2.35]). In the older cohort, sitagliptin did not significantly impact the primary composite (1.10 [0.89-1.36]), death (1.05 [0.83-1.32]), heart failure hospitalization (0.99 [0.65-1.49]), severe hypoglycemia (1.03 [0.62-1.71]), rates of acute pancreatitis and pancreatic cancer, or serious adverse events. CONCLUSIONS: Among older patients with well-controlled type 2 diabetes and cardiovascular disease, sitagliptin had neutral effects on cardiovascular risk and raised no significant safety concerns.

Effect of Sitagliptin on Cardiovascular Outcomes in Type 2 Diabetes.

BACKGROUND: Data are lacking on the long-term effect on cardiovascular events of adding sitagliptin, a dipeptidyl peptidase 4 inhibitor, to usual care in patients with type 2 diabetes and cardiovascular disease. METHODS: In this randomized, double-blind study, we assigned 14,671 patients to add either sitagliptin or placebo to their existing therapy. Open-label use of antihyperglycemic therapy was encouraged as required, aimed at reaching individually appropriate glycemic targets in all patients. To determine whether sitagliptin was noninferior to placebo, we used a relative risk of 1.3 as the marginal upper boundary. The primary cardiovascular outcome was a composite of cardiovascular death, nonfatal myocardial infarction, nonfatal stroke, or hospitalization for unstable angina. RESULTS: During a median follow-up of 3.0 years, there was a small difference in glycated hemoglobin levels (least-squares mean difference for sitagliptin vs. placebo, -0.29 percentage points; 95% confidence interval [CI], -0.32 to -0.27). Overall, the primary outcome occurred in 839 patients in the sitagliptin group (11.4%; 4.06 per 100 person-years) and 851 patients in the placebo group (11.6%; 4.17 per 100 person-years). Sitagliptin was noninferior to placebo for the primary composite cardiovascular outcome (hazard ratio, 0.98; 95% CI, 0.88 to 1.09; P<0.001). Rates of hospitalization for heart failure did not differ between the two groups (hazard ratio, 1.00; 95% CI, 0.83 to 1.20; P=0.98). There were no significant between-group differences in rates of acute pancreatitis (P=0.07) or pancreatic cancer (P=0.32). CONCLUSIONS: Among patients with type 2 diabetes and established cardiovascular disease, adding sitagliptin to usual care did not appear to increase the risk of major adverse cardiovascular events, hospitalization for heart failure, or other adverse events. (Funded by Merck Sharp & Dohme; TECOS ClinicalTrials.gov number, NCT00790205.).

Type 1 diabetes and cardiovascular disease.

The presence of cardiovascular disease (CVD) in Type 1 diabetes largely impairs life expectancy. Hyperglycemia leading to an increase in oxidative stress is considered to be the key pathophysiological factor of both micro- and macrovascular complications. In Type 1 diabetes, the presence of coronary calcifications is also related to coronary artery disease. Cardiac autonomic neuropathy, which significantly impairs myocardial function and blood flow, also enhances cardiac abnormalities. Also hypoglycemic episodes are considered to adversely influence cardiac performance. Intensive insulin therapy has been demonstrated to reduce the occurrence and progression of both micro- and macrovascular complications. This has been evidenced by the Diabetes Control and Complications Trial (DCCT) / Epidemiology of Diabetes Interventions and Complications (EDIC) study. The concept of a metabolic memory emerged based on the results of the study, which established that intensified insulin therapy is the standard of treatment of Type 1 diabetes. Future therapies may also include glucagon-like peptide (GLP)-based treatment therapies. Pilot studies with GLP-1-analogues have been shown to reduce insulin requirements.

Predictors of cardiovascular events in a contemporary population with impaired glucose tolerance: an observational analysis of the Nateglinide and Valsartan in impaired glucose tolerance outcomes research (NAVIGATOR) trial.

OBJECTIVES: Risk factors for cardiovascular events are well established in general populations and those with diabetes but have been sparsely studied in impaired glucose tolerance (IGT). We sought to identify predictors of (1) a composite cardiovascular outcome (cardiovascular death, non-fatal myocardial infarction and non-fatal stroke) and (2) cardiovascular death, among patients with IGT. DESIGN: We studied participants enrolled in the Nateglinide and Valsartan in Impaired Glucose Tolerance Outcomes Research (NAVIGATOR) trial. Predictors of cardiovascular events were identified in observational analyses. SETTING: Clinical trial participants in 40 countries. PARTICIPANTS: 9306 participants with biochemically confirmed IGT at high risk of cardiovascular events participated in NAVIGATOR. PRIMARY AND SECONDARY OUTCOME MEASURES: Cox proportional hazard regression models were constructed using variables (demographic data, medical history, clinical features, biochemical results and ECG findings) recorded at baseline to identify variables associated with and predictive of cardiovascular events. RESULTS: Over 6.4 years, 639 (6.9%) participants experienced a cardiovascular event, and 244 (2.6%) cardiovascular death. While predictors of both outcomes included established risk factors such as existing cardiovascular disease, male gender, older age, current smoking status and higher low-density lipoprotein cholesterol, other variables such as reduced estimated glomerular filtration rate, previous thromboembolic disease, atrial fibrillation, higher urinary albumin/creatinine ratio and chronic obstructive pulmonary disease were also important predictors. Glycaemic measures were not predictive of cardiovascular events. c-Statistics for predicting cardiovascular events and cardiovascular death were 0.74 and 0.82, respectively. This compares with c-statistics for cardiovascular events and cardiovascular death of 0.65 and 0.71, respectively, using the classical Framingham risk factors of age, total cholesterol, high-density lipoprotein cholesterol, systolic blood pressure, treatment for hypertension and smoking status. CONCLUSIONS: The most powerful independent predictors of cardiovascular events in IGT included both established risk factors and other variables excluding measures of glycaemia, allowing effective identification of high-risk individuals.

Screening for overt diabetes by oral glucose tolerance test: stratification by fasting blood glucose and patients' age improve practicability of guidelines in cardiological routine.

BACKGROUND/OBJECTIVES: Guidelines recommend screening all patients with cardiovascular disease by oral glucose tolerance test (OGTT). Due to its time-consuming protocol, costs and overall inconvenience performance of OGTT is limited in cardiological routine. Thus, we aimed to identify easily available parameters that could help to reduce the numbers of OGTT needed. METHODS: OGTTs (n=1215) were performed in all patients without known type 2 diabetes mellitus (T2DM) that were submitted to the heart center Wuppertal with known or suspected coronary artery disease for an elective coronary angiography from January to October 2007. RESULTS: 31.4% had normal glucose tolerance; prediabetes was present in 50.7%, whereas 17.9% were newly diagnosed with T2DM. Thus, 998 OGTTs did not result in the new diagnosis of so far undiagnosed T2DM. Multiple logistic regression and receiver operated characteristic analyses demonstrated that fasting blood glucose (FBG)≥ 90 mg/dl and age ≥ 55 years were predictive for so far undiagnosed T2DM. Considering these two parameters 81.1% (=sensitivity) of so far undiagnosed T2DM patients would have been identified (specificity=63.4%) and the number of OGTTs could have been reduced from 1215 to 541. CONCLUSIONS: About 70% of patients were newly diagnosed with impaired glucose metabolism. FBG ≥ 90 mg/dl and age ≥ 55 years were predictive for so far undiagnosed T2DM and OGTTs could be reduced by 55.5%. This should alleviate the implementation of the current guidelines in daily cardiological practice.

Is the current therapeutic armamentarium in diabetes enough to control the epidemic and its consequences? What are the current shortcomings?

The prevalence of diabetes is expected to rise together with an increase in morbidity and a reduction in life expectancy. A leading cause of death is cardiovascular disease, and hypertension and diabetes are additive risk factors for this complication. Selected treatment options should neither increase cardiovascular risk in patients with diabetes, nor increase risk of hyperglycaemia in patients with hypertension. The efficacy of present antihyperglycaemic agents is limited and new therapies, such as incretin-targeted agents, are under development. Even though most patients do not achieve glycated haemoglobin targets, trial data show that such interventions reduce the incidence of macrovascular events; however, intensive lowering may be detrimental in patients with existing cardiovascular disease. Currently available oral drugs do not address the key driver of type 2 diabetes--loss of functional beta-cell mass. In the future, new oral treatments must improve this, whilst providing durable blood glucose control and long-term tolerability.

Twelve- and 52-week efficacy of the dipeptidyl peptidase IV inhibitor LAF237 in metformin-treated patients with type 2 diabetes.

OBJECTIVE: To assess the 12- and 52-week efficacy of the dipeptidyl peptidase IV inhibitor LAF237 versus placebo in patients with type 2 diabetes continuing metformin treatment. RESEARCH DESIGN AND METHODS: We conducted a 12-week, randomized, double-blind, placebo-controlled trial in 107 patients with type 2 diabetes with a 40-week extension in those completing the core study and agreeing, together with the investigator, to extend treatment to 1 year. Placebo (n=51) or LAF237 (50 mg once daily, n=56) was added to ongoing metformin treatment (1,500-3,000 mg/day). HbA1c and fasting plasma glucose (FPG) were measured periodically, and standardized meal tests were performed at baseline, week 12, and week 52. RESULTS: In patients randomized to LAF237, baseline HbA1c averaged 7.7 +/- 0.1% and decreased at week 12 (Delta=-0.6 +/- 0.1%), whereas HbA1c did not change from a baseline of 7.9 +/- 0.1% in patients given placebo (between-group difference in DeltaHbA1c=-0.7 +/- 0.1%, P <0.0001). Mean prandial glucose and FPG were significantly reduced in patients receiving LAF237 versus placebo by 2.2 +/- 0.4 mmol/l (P <0.0001) and 1.2 +/- 0.4 mmol/l (P=0.0057), respectively, but plasma insulin levels were not affected. At end point of the extension, the between-group differences in change in mean prandial glucose, insulin, and FPG were -2.4 +/- 0.6 mmol/l (P=0.0001), 40 +/- 16 pmol/l (P=0.0153), and -1.1 +/- 0.5 mmol/l (P=0.0312), respectively. HbA1c did not change from week 12 to week 52 in LAF237-treated patients (n=42) but increased in participants given placebo (n=29). The between-group difference in DeltaHbA1c after 1 year was -1.1 +/- 0.2% (P <0.0001). CONCLUSIONS: Data from this study demonstrate that LAF237 effectively prevents deterioration of glycemic control when added to metformin monotherapy in type 2 diabetes.

Intensification of therapeutic approaches reduces mortality in diabetic patients with acute myocardial infarction: the Munich registry.

OBJECTIVE: The myocardial infarction (MI) registry of the Academic Schwabing Hospital, Munich, investigates the hospital course of diabetic and nondiabetic patients with acute MI. The aim of this study was to improve quality care management and to compare hospital mortality and therapeutic approaches (i.e., PTCA, stenting, GPIIb/IIIa receptor antagonists, glucose-insulin infusion). RESEARCH DESIGN AND METHODS: Data of diabetic patients and nondiabetic patients were analyzed. All diabetic and nondiabetic subjects who were admitted in 1999 and 2001 were included: 1999, 126 (38%) diabetic and 204 (62%) nondiabetic patients; 2001, 91 (31%) diabetic and 205 (59%) nondiabetic patients. RESULTS: In 1999, coronary angiography (P < 0.01), percutaneous transluminal coronary angioplasty (PTCA) (P < 0.001), and stenting (P < 0.001) were performed less frequently in diabetic than in nondiabetic patients. During this period, total hospital mortality (29 vs. 16%, P < 0.01) and mortality within 24 h after admission (14 vs. 5%, P = 0.01) were higher in diabetic than in nondiabetic patients. In 2001, frequencies of coronary angiography, PTCA, and stenting were increased in diabetic patients (P < 0.001 vs. 1999), and the interventions were comparable with those performed in nondiabetic patients. Furthermore, glucose-insulin infusion was administered in 46% of diabetic subjects. In 2001, total hospital mortality decreased to 17% in diabetic subjects (P = 0.028 vs. 1999) and mortality within 24 h after admission declined to 4% (P = 0.027 vs. 1999). Logistic regression analysis revealed that an increase in the number of therapeutic approaches (also when adjusted for clinical variables) is associated with a reduction in mortality of diabetic patients with acute MI (adjusted odds ratio 0.14, P < 0.0001). CONCLUSIONS: Intensification of multiple advanced therapeutic strategies in diabetic patients with acute MI enables a substantial reduction in hospital mortality. The enforcement leads to rates of hospital mortality that are comparable to those of nondiabetic patients.

Dysregulation of coronary microvascular reactivity in asymptomatic patients with type 2 diabetes mellitus.

In diabetic patients, a number of studies have suggested an impairment of vascular reactivity in response to vasodilatory stimuli. The pattern of dysregulation at the coronary microcirculatory level, however, has not been clearly defined. Thus, it was the aim of this study to characterise coronary microvascular function non-invasively in a homogeneous group of asymptomatic type 2 diabetic patients. In 46 patients with type 2 diabetes, myocardial blood flow (MBF) was quantified at baseline, in response to cold pressor test (CPT) and during adenosine-mediated vasodilation using positron emission tomography and nitrogen-13 ammonia. None of the patients had been treated with insulin, and none had symptoms of cardiac disease. Decreased MBF during CPT, indicating microvascular dysregulation, was observed in 16 patients (CPT-), while 30 patients demonstrated increased MBF during CPT (CPT+). Response to CPT was mildly, but significantly correlated with response to adenosine ( r=0.44, P=0.0035). There was no difference in HbA1c, serum lipid levels or serum endothelial markers between the groups. Microvascular dysregulation in the CPT- group was associated with elevated baseline MBF ( P<0.0001), reduced baseline vascular resistance ( P=0.0026) and an abnormal increase in resistance during CPT ( P=0.0002). In conclusion, coronary microvascular dysregulation is present in approximately one-third of asymptomatic, non-insulin-treated type 2 diabetic patients. Elevated baseline blood flow and reduced microvascular resistance at rest are characteristics of this dysregulation. These data suggest a state of activation of endothelial-dependent vasodilation at baseline which appears to limit the flow response to stress conditions.