The posttreatment basal GH concentration less than 2.5 microg/liter in acromegalic patients is associated with a normal lifespan. Excess mortality is confined to poorly controlled patients and possibly those who have received conventional radiotherapy.

Disturbances of coronary circulation have been reported in diabetic patients with microvascular complications but without obstructive coronary atherosclerosis. The aim of the present study was to investigate coronary flow reserve in young adult patients with IDDM but without microalbuminuria and diabetic autonomic neuropathy. Coronary flow reserve was determined in 12 nonsmoking male patients with IDDM (age 30.0 +/- 6.6 years) and 12 healthy matched volunteers. Groups were similar with respect to blood pressure and serum lipid concentrations, and no subject had a positive family history of coronary heart disease. The patients with IDDM had normal exercise echocardiography and autonomic nervous function tests. Five patients had minimal background retinopathy, and none had microalbuminuria. Positron emission tomography and [15O]H2O were used to measure myocardial blood flow at rest and after dipyridamole administration. The studies were performed during euglycemic hyperinsulinemia (serum insulin approximately 70 mU/l). The baseline myocardial blood flow was similar in patients with IDDM and in control subjects (0.84 +/- 0.18 vs. 0.88 +/- 0.25 ml x g(-1) x min(-1), NS). The myocardial blood flow during hyperemia was 29% lower in patients with IDDM (3.17 +/- 1.57) compared with the control subjects (4.45 +/- 1.37 ml x g(-1) x min(-1), P < 0.05). Consequently, coronary flow reserve (the ratio of flow during hyperemia and at rest) was lower in diabetic patients than in control subjects (3.76 +/- 1.69 vs. 5.31 +/- 1.86, P < 0.05) and the total coronary resistance during hyperemia was higher in diabetic patients (53.7 +/- 31.5) compared with the control subjects (31.4 +/- 11.6 mmHg x min x g x ml(-1), P < 0.05). The coronary flow reserve was similar in diabetic patients with and without mild background retinopathy. No association was found between the coronary flow reserve and serum lipid or HbA1c values in either group. Coronary flow reserve is impaired in young adult males with IDDM and no or minimal microvascular complications and without any evidence of coronary heart disease. This abnormality cannot be explained by standard coronary heart disease risk factors. The results imply early impairment of coronary vascular reactivity in IDDM patients, which may represent an early precursor of future coronary heart disease or may contribute to the pathogenesis of diabetic cardiomyopathy.

Defects in insulin stimulation of blood flow have been suggested to contribute to insulin resistance. To directly test whether glucose uptake can be altered by changing blood flow, we infused bradykinin (27 g over 100 min), an endothelium-dependent vasodilator, into the femoral artery of 12 normal subjects (age 25 Ϯ 1 yr, body mass index 22 Ϯ 1 kg ր m 2 ) after an overnight fast ( n ϭ 5) and during normoglycemic hyperinsulinemic ( n ϭ 7) conditions (serum insulin 465 Ϯ 11 pmol ր liter, 0-100 min). Blood flow was measured simultaneously in both femoral regions using and PET. During hyperinsulinemia, muscle blood flow was 58% higher in the bradykinin-infused (38 Ϯ 9 ml ր kg muscle и min) than in the control leg (24 Ϯ 5, P Ͻ 0.01). Femoral muscle glucose uptake was identical in both legs (60.6 Ϯ 9.5 vs. 58.7 Ϯ 9.0 mol ր kg и min, bradykinin-infused vs. control leg, NS). Glucose extraction by skeletal muscle was 44% higher in the control (2.6 Ϯ 0.2 mmol ր liter) than the bradykinin-infused leg (1.8 Ϯ 0.2 mmol ր liter, P Ͻ 0.01). When bradykinin was infused in the basal state, flow was 98% higher in the bradykinin-infused (58 Ϯ 12 ml ր kg muscle и min) than the control leg (28 Ϯ 6 ml ր kg muscle и min, P Ͻ 0.01) but rates of muscle glucose uptake were identical in both legs (10.1 Ϯ 0.9 vs. 10.6 Ϯ 0.8 mol ր kg и min). We conclude that bradykinin increases skeletal muscle blood flow but not muscle glucose uptake in vivo. These data provide direct evidence against the hypothesis that blood flow is an independent regulator of insulin-stimulated glucose uptake in humans. ( J. Clin. Invest . 1996. 97:1741-1747.)

Detection of early vascular changes indicated by lowered coronary flow reserve (CFR) would allow early treatment and prevention of atherosclerosis. The purpose of this study was to test whether it is possible to reproducibly measure CFR with transthoracic Doppler echocardiography (TTE) in healthy volunteers. We measured CFR using dipyridamole infusion in ten healthy male volunteers with two methods: TTE and positron emission tomography (PET) with oxygen-15-labelled water (group A). However, CFR was assessed twice with TTE in eight healthy male volunteers (group B) to study the reproducibility of this method. We compared CFRs obtained using TTE flow measurements in the left anterior descending coronary artery (LAD) and PET flow measurements in the corresponding myocardial area. Coronary flow in LAD could be measured in all subjects using TTE. By TTE, an average CFR based on peak diastolic flow velocity (PDV) was 2.72 +/- 1.16, mean diastolic flow velocity (MDV) 2.56 +/- 1.06 and velocity time integral (VTI) 1.87 +/- 0.49. The results were reproducible in two repeated TTE studies (coefficient of variation in MDV 6.1 +/- 4.3%, n=8). By PET, CFR was 2.52 +/- 0.84. CFR assessed by TTE correlated closely with that measured by PET (MDV r=0.942, P<0.001; PDV r=0.912, P<0.002 and VTI r=0.888, P<0.006) and intraclass correlation was 0.929 (MDV) and tolerance limits for differences of CFRs was -0.78 to 0.72. We show that CFR measured by TTE has an excellent correlation with CFR measured by PET. We also found that TTE measurements of CFR were highly reproducible.

These results demonstrate reduced coronary reactivity present in young asymptomatic men with borderline hypertension and no signs of hypertension-induced angina or left ventricular hypertrophy. Because baseline basal myocardial blood flow was unchanged, the reduction in coronary flow reserve depends on an impaired maximal vasodilator capacity.

No abstract

Signs or symptoms of macrovascular disease are frequently found even prior to the development of noninsulin-dependent diabetes mellitus (NIDDM) [1]. This suggests that coronary heart disease (CHD) and NIDDM share a pathophysiologic feature, which predisposes to both diseases. Classic risk factors such as serum cholesterol, age, gender, hypertension and smoking explain only a fraction of the 2±4-fold increase in cardiovascular mortality in patients with NIDDM [1,2]. Insulin resistance, usually measured by quantitating the rate of insulin-stimulated glucose uptake, qualifies as the underlying pathophysiologic abnormality for both CHD and NIDDM, since it predicts, independent of other risk factors, both disorders [3,4].The mechanisms linking insulin resistance to CHD are unclear but could involve lipid abnormalities such as an increase in the concentration of atherogenic small dense LDL particles, which accompanies insu- Diabetologia (1998) Summary Skeletal muscle insulin resistance and coronary heart disease (CHD) often precede non-insulin-dependent diabetes mellitus (NIDDM). A recent study showed the myocardium of patients with CHD to be insulin resistant, independent of blood flow. We determined whether myocardial insulin resistance is a feature of NIDDM patients with no CHD. Skeletal muscle and myocardial glucose uptake were determined in 10 patients with NIDDM and 9 ageand weight-matched normal men of similar age and body mass index men using [18 F]-2-fluoro-2-deoxy-dglucose and positron emission tomography under normoglycaemic hyperinsulinaemic conditions. Whole body glucose uptake, as determined by the euglycaemic clamp technique, was significantly lower in the patients with NIDDM (35 ± 3 mmol/kg body weight´min) than the normal subjects (45 ± 3 mmol/ kg body weight´min, p < 0.02). Insulin-stimulated femoral muscle glucose uptake was significantly lower in the patients with NIDDM (71 ± 6 mmol/kg muscle´min) than in the normal subjects (96 ± 5 mmol/ kg muscle´min, p < 0.01). Whole body glucose uptake was correlated with femoral muscle glucose uptake in the entire group (r = 0.76, p < 0.001), in patients with NIDDM and in normal subjects. Rates of insulin-stimulated myocardial glucose uptake were comparable between the patients with NIDDM (814 ± 76 mmol/kg muscle´min) and the normal subjects (731 ± 63 mmol/kg muscle´min, p > 0.4). Whole body or femoral muscle, and myocardial glucose uptake were not correlated in all subjects, patients with NIDDM or normal subjects. We conclude that insulin resistance of the myocardium is not a feature of uncomplicated NIDDM. [Diabetologia (1998) 41: 555-559] Keywords Myocardium, insulin resistance, non-insulin-dependent diabetes mellitus, positron emission tomography.

BackgroundNo school-based physical activity (PA) interventions among older adolescents have demonstrated long-term effectiveness, and few of them so far have addressed sedentary behaviour (SB). Based on behavioural theories and evidence, we designed a multi-level intervention to increase PA and decrease SB among vocational school students. This study investigates feasibility and acceptability of two main intervention components and research procedures. We also examine uptake of behaviour change techniques (BCTs) by the participants.MethodsDesign was an outcome assessor blinded, cluster-randomised controlled trial. Four classes of students (matched pairs) were randomised into one intervention and one control arm. The intervention consisted of (1) a 6-h group-based intervention for students, (2) two 2-h training workshops to reduce their students’ sitting in class for teachers, and (3) provision of light PA equipment in classrooms. At baseline (T1), mid-intervention (T2) at 3 weeks, post-intervention (T3) and 6 months after baseline (T4) we measured hypothesised psychosocial mediators and self-reported PA and sitting. Objective assessment of PA and SB (7-day accelerometry) was conducted at T1, T3 and T4. Body composition (bioimpedance) was measured at T1 and T4. Students and teachers in the intervention arm filled in acceptability questionnaires at T3.ResultsRecruitment rate was 64% (students) and 88.9% (teachers), and at T3, all post-intervention measurements were completed by 33 students (retention 76.7%) and 15 teachers (retention 93.8%). Acceptability ratings of sessions were high (students M = 6.29, scale 1–7), and data collection procedures were feasible. Intervention arm students reported increased use of BCTs, but uptake of some key BCTs was suboptimal. BCT use correlated highly with objective measures of PA. Based on both self-report and student evaluation, teachers in the intervention arm increased the use of sitting reduction strategies at post-intervention and T4 follow-up (p < .05).ConclusionsWe detected willingness of the target groups to participate, good response rates to questionnaires, adequate retention, as well as acceptability of the trial protocol. Investigation of BCT use among students helped further enhance intervention procedures to promote BCT use. After making necessary modifications identified, intervention effectiveness can next be tested in a definitive trial.Trial registration ISRCTN34534846. Registered 23 May 2014. Retrospectively registered.Electronic supplementary materialThe online version of this article (doi:10.1186/s12966-017-0484-0) contains supplementary material, which is available to authorized users.