Plasma N-terminal pro-brain natriuretic peptide as a major risk marker for cardiovascular disease in patients with type 2 diabetes and microalbuminuria

Aims/hypothesis We examined whether plasma N-terminal probrain natriuretic peptide (NT-proBNP) predicts cardiovascular outcome in patients with type 2 diabetes.Methods A total of 160 microalbuminuric type 2 diabetic patients (mean age 55.1 years [SD 7.2], 119 men) were enrolled in the Steno-2 Study examining the effect of multifactorial treatment, and were divided into two groups according to baseline levels of plasma NT-proBNP below or above the median for the cohort, which was followed for an average of 7.8 years. Cardiovascular outcome was a composite of cardiovascular mortality, myocardial infarction, stroke, revascularisation procedures in the heart or legs, and amputations.Results In the whole group, plasma NT-proBNP being above the median was associated with an increased risk of cardiovascular disease during follow-up, with an unadjusted hazard ratio of 4.4 (95% CI 2.3–8.4; p<0.0001). A decrease in plasma NT-proBNP of 10 pg/ml during the first 2 years of intervention was associated with a 1% relative reduction in the primary endpoint (p<0.001). Despite polypharmacological treatment targeting cardiovascular disease, the mean plasma NT-proBNP level increased during follow-up.Conclusions/interpretation We conclude that high plasma NT-proBNP is a major risk marker for cardiovascular disease in patients with type 2 diabetes and microalbuminuria.     

Plasma N-terminal pro-B-type natriuretic peptide and mortality in type 2 diabetes

Aims/hypothesis Raised N-terminal pro-B-type natriuretic peptide (NT-proBNP) is associated with a poor cardiac outcome in non-diabetic populations. Elevated NT-proBNP predicts excess morbidity and mortality in diabetic patients with an elevated urinary albumin excretion rate. This study investigated the prognostic value of NT-proBNP in a cohort of type 2 diabetic patients. Subjects, materials and methods In a prospective observational follow-up study, 315 type 2 diabetic patients with normoalbuminuria (n=188), microalbuminuria (n=80) and macroalbuminuria (n=47) at baseline were followed for a median (range) of 15.5 (0.2–17.0) years. Plasma NT-proBNP concentrations were determined by immunoassay at baseline. Endpoints were overall and cardiovascular mortality. Results Of the patients, 162 died (51%), 119 of them (74%) due to cardiovascular causes. All-cause mortality was increased in patients with NT-proBNP in the second and third tertiles (hazard ratios [95% CI] compared with the first tertile, 1.70 [1.08–2.67] and 5.19 [3.43–7.88], p<0.001). These associations persisted after adjustment for urinary albumin excretion rate, glomerular filtration rate and conventional cardiovascular risk factors (covariate adjusted hazard ratios 1.46 [0.91–2.33] and 2.54 [1.56–4.14], p<0.001). This increased mortality was attributable to more cardiovascular deaths in the second and third NT-proBNP tertile (unadjusted hazard ratios 1.63 [0.96–2.77] and 4.88 [3.01–7.91], p<0.001; covariate adjusted 1.37 [0.79–2.37] and 2.26 [1.27–4.02], p=0.01). When patients with normo-, micro- and macroalbuminuria were analysed separately, NT-proBNP levels above the median (62 ng/l) were consistently associated with increased overall and cardiovascular mortality in all three groups (p<0.001). Conclusions/interpretation In patients with type 2 diabetes, elevated circulating NT-proBNP is a strong predictor of the excess overall and cardiovascular mortality, this predictor status being independent of urinary albumin excretion rate and conventional cardiovascular risk factors.     

Apolipoprotein(a) and cardiovascular disease in Type 2 (non-insulin-dependent) diabetic patients with and without diabetic nephropathy

Summary The relative mortality from cardiovascular disease is on average increased five-fold in Type 2 (non-insulin-dependent) diabetic patients with diabetic nephropathy compared to non-diabetic subjects. We assessed the possible contribution of dyslipidaemia in general and elevated serum apolipoprotein(a) (apo(a)) in particular. Type 2 diabetic patients with normo-, micro- and macroalbuminuria were compared with healthy subjects. Each group consisted of 37 subjects matched for age, sex and diabetes duration. Serum creatinine in the nephropathy group was 105 (54–740) mol/l. The prevalence of ischaemic heart disease (resting ECG, Minnesota, Rating Scale) was 57, 35, 19 and 2% in macro-, micro- and normoalbuminuric diabetic patients and healthy subjects, respectively. The prevalence of ischaemic heart disease was higher in all diabetic groups as compared to healthy subjects (p<0.05), and higher in macroalbuminuric as compared to normoalbuminuric diabetic patients (p<0.01). There was no significant difference between apo(a) in the four groups: 161 (10–1370), 191 (10–2080), 147 (10–942), 102 (10–1440) U/l (median (range)) in macro-, micro- and normoalbuminuric groups and healthy subjects. Serum total-cholesterol, HDL-cholesterol and LDL-cholesterol were not significantly different when comparing healthy subjects and each diabetic group. Apolipoprotein A-I was lower (p<0.05) in all diabetic groups as compared to healthy subjects (nephropathy vs healthy subjects): 1.50±0.25 vs 1.69±0.32 g/l (mean ± SD). Triglyceride was higher (p<0.05) in patients with nephropathy and microalbuminuria as compared to healthy subjects (nephropathy vs healthy subjects): 2.01 (0.66–14.7) vs 1.09 (0.41–2.75) mmol/l (median (range)). Apolipoprotein B was higher (p<0.02) in patients with nephropathy as compared to the other three groups (nephropathy vs healthy subjects): 1.54±0.47 vs 1.33±0.30 g/l. In conclusion, our case-control study has confirmed that Type 2 diabetic patients with increased urinary albumin excretion frequently suffer from dyslipidaemia and cardiovascular disease. However, our study revealed no significant elevation in serum concentration of apo(a) in patients with diabetic nephropathy, but numbers were small.     

Effect of improved metabolic control on loss of kidney function in Type 1 (insulin-dependent) diabetic patients: an update of the Steno studies

Summary We re-examined 69 of the 70 patients entering the two independent Steno Studies of effects of improved metabolic control on progression of late diabetic complications. They were analysed according to an intent to treat after follow-up for 8 years (Steno Study 1) and 5 years (Steno Study 2). The glycaemic control had improved in the insulin infusion group compared with the conventional treatment group (mean HbA_1c) by 2.0±0.6% vs 0.7±1.2 in Steno Study 1 and by 1.8±1.2% vs 0.4±1.3 (p<0.01) in Steno Study 2. In the insulin infusion groups three patients had died during episodes of ketoacidosis. These were not caused by malfunction of the insulin infusion pumps. In the conventional treatment groups, three patients suffered five cardiovascular events causing two deaths. From the sixth month of Steno Study 1 the annual change of the glomerular filtration rate was –3.7 (–5.4 to –2.0) ml·min^–1·1.73 m^–2 vs –1.0 (–2.1 to –0.1) (conventional vs insulin infusion group, mean (95% confidence interval, p<0.01)). The change in urinary albumin excretion was associated with the glycaemic control (n=69, r=0.49, p<0.0002). No progression was observed among 32 patients with low range microalbuminuria (30 to 99 mg/24 h). Among the 19 patients with an initial albumin excretion between 100 and 300 mg/24 h, progression of complications was more frequent during conventional treatment (n=10) vs insulin infusion (n=9): Clinical nephropathy (10 of 10 vs 2 of 9, p<0.01) and arterial hypertension (7 of 10 vs 1 of 9, p<0.01). The glomerular filtration rate declined during conventional treatment by –23 (–42 to –4) ml·mm^–1·1.73 m^–2 (p<0.05) but not during insulin infusion (–13 (–31 to 5) NS). These results suggest that patients at risk of nephropathy should be offered near normal glycaemic control in order to preserve their kidney function.     

Plasma osteoprotegerin levels predict cardiovascular and all-cause mortality and deterioration of kidney function in type 1 diabetic patients with nephropathy

Aims/hypothesis  The bone-related peptide osteoprotegerin is produced by vascular cells and is involved in the process of vascular calcification. The aim of this study was to investigate the predictive value of plasma levels of osteoprotegerin in relation to mortality, cardiovascular events and deterioration in kidney function in patients with type 1 diabetes. Methods  This prospective observational follow-up study included 397 type 1 diabetic patients with overt diabetic nephropathy (243 men; age [mean±SD] 42.1 ± 10.6 years, duration of diabetes 28.3 ± 9.9 years, GFR 67 ± 28 ml min⁻¹ 1.73 m²) and a group of 176 patients with longstanding type 1 diabetes and persistent normoalbuminuria (105 men; age 42.6 ± 9.7 years, duration of diabetes 27.6 ± 8.3 years). Results  The median (range) follow-up period was 11.3 (0.0–12.9) years. Among patients with diabetic nephropathy, individuals with high osteoprotegerin levels (fourth quartile) had significantly higher all-cause mortality than patients with low levels (first quartile) (covariate-adjusted hazard ratio [HR] 3.00 [1.24–7.27]). High osteoprotegerin levels also predicted cardiovascular mortality (covariate-adjusted HR 4.88 [1.57–15.14]). Furthermore, patients with high osteoprotegerin levels had significantly higher risk of progression to end-stage renal disease than patients with low levels (covariate-adjusted HR 4.32 [1.45–12.87]). In addition, patients with high levels of plasma osteoprotegerin had an elevated rate of decline in GFR. Conclusions/interpretation  High levels of osteoprotegerin predict all-cause and cardiovascular mortality in patients with diabetic nephropathy. Furthermore, high levels of osteoprotegerin predict deterioration of kidney function towards end-stage renal disease.     

Pharmacokinetic,insulinotropic, and glucagonostatic properties of GLP-1 [7–36 amide] after subcutaneous injection in healthy volunteers. Dose-response-relationships

Summary Intravenous infusions of glucagon-like peptide 1 (GLP-1) [7–36 amide] are glucose-dependently insulinotropic and glucagonostatic and normalize plasma glucose concentrations in non-insulin-dependent diabetic patients. It was the aim of this study to investigate whether subcutaneous GLP-1 [7–36 amide] also has an influence on insulin and glucagon secretion, and which doses are required for significant effects. Therefore, eight healthy volunteers (24±2 years, body mass index [BMI] 21.9±2.3 kg/ m²) were studied in the fasting state on five occasions in randomized order. Placebo (0.9% NaCl with 1% human serum albumin) or GLP-1 [7–36 amide] in doses of 0.15, 0.5, 1.5 or 4.5 nmol/kg body weight (volume 1 ml or, at the highest dose, 2 ml) was administered subcutaneously. An intravenous glucose bolus (0.33 g/kg body weight) was injected 30 min later. Blood was drawn for the measurement of glucose, insulin, C-peptide, GLP-1 [7–36 amide], and glucagon using specific radioimmunoassays. There were dose-related increments in GLP-1 [7–36 amide] concentrations (p<0.0001). However, basal values were reached again after 90–120 min. Before glucose administration, insulin (p<0.0001) and C-peptide (p<0.0004) increased, whereas glucagon (p = 0.0018) and glucose (p<0.0001) decreased in a dose-dependent manner. After glucose stimulation, integrated increments in insulin (p=0.0007) and C-peptide (p=0.02) were augmented and k_G-values increased (p<0.0001) in a dose-related fashion. The extent of reactive hypoglycaemia was related to the GLP-1 [7–36 amide] dose. With the highest GLP-1 [7–36 amide] dose, at the time of peak plasma concentrations, most volunteers felt unwell, and nausea and vomiting were observed in four subjects. In conclusion, subcutaneous GLP-1 [7–36 amide] is also able to stimulate insulin and inhibit glucagon secretion, thereby altering glucose assimilation. However, with unmodified GLP-1 [7–36 amide], the duration of action is short, and with high doses side effects are common.Abbreviations BMI Body mass index - GLP-1 glucagon-like peptide-1 - RIA radioimmunoassay - RM-ANOVA repeated-measures analysis of variance - GIP gastric inhibitory polypeptide     

Leucocyte sodium efflux and electrolyte content in insulin treated diabetes

Summary Leucocyte sodium efflux and sodium content were studied in 41 insulin treated diabetic patients and compared to 41 age, body mass index and blood pressure matched nondiabetic control subjects. Fasting leucocyte Na ouabain-sensitive efflux rate constants were lower in diabetic patients (median [range] 2.30 [1.04–3.73] versus 2.45 [1.57–3.95] h^–1, p<0.04) suggesting a reduced sodium pump activity. The ²²Na ouabain-insensitive efflux rate constant which reflects passive sodium efflux was raised in insulin treated diabetes (0.92 [0.42–1.73] versus 0.79 [0.28–1.49] h^–1, p<0.01). Leucocyte sodium content was raised in the diabetic patients (47.7 [26.9–93.4] versus 26.5 [15.9–67.7] mmol/kg, p<0.0001). Abnormal cellular sodium handling could lead to hypertension or other complications in diabetes.     

Prevalence of hypertension in Type 1 (insulin-dependent) diabetes mellitus

Summary The prevalence of hypertension in a representative sample (n=10202) of the Danish general population aged 16–59 years was assessed to 4.4% based on three blood pressure readings. In Type 1 (insulin-dependent) diabetic patients of similar age (n=1703) the prevalence was determined in a similar way to 14.7% (p<0.00001). The excess prevalence in Type 1 diabetic patients was due to hypertension in patients with incipient and clinical nephropathy as the prevalence of hypertension among diabetic patients with normal urinary albumin excretion (essential hypertension) was 3.9%, similar to that observed in the general population. The patients with Type 1 diabetes and essential hypertension had higher systolic (146±19 vs 133±18 mmHg, p<0.00001) and diastolic blood pressure (87±12 vs 79±7mmHg, p<0.00001), but less changes in the eye background than patients with incipient nephropathy (urinary albumin excretion 30–300 mg/24 h) (p<0.03), indicating that the two groups were also different with respect to other microangiopathic lesions. Patients with essential hypertension were defined as having a normal urinary albumin excretion before and during antihypertensive treatment (if any). They were followed-up for a 58 (6–234) month period. We confirmed that hypertension is more common among Type 1 diabetic patients than in the general population and found the prevalence of essential hypertension similar in Type 1 diabetic patients to the non-diabetic population. This supports our hypothesis that hypertension is very unlikely to be the cause of diabetic nephropathy.     

Effect of insulin on renal sodium handling in hyperinsulinaemic Type 2 (non-insulin-dependent) diabetic patients with peripheral insulin resistance

Summary The sodium retaining effect of insulin was studied in ten Type 2 (non-insulin-dependent) diabetic patients (mean age 56 (43–73) years, mean body mass index 29.5 (24.2–33.7) kg/m²) and eight age-matched control subjects (mean age 57 (43–68) years, mean body mass index 23.4 (20.8–26.6) kg/m²). The renal clearances of ^99mTc-DTPA, lithium, sodium and potassium were measured over a basal period of 90 min. Then insulin was infused at a rate of 40 mU·mirr^–1·m^–2. After an equilibration period of 90 min, the clearance measurements were repeated during a new 90 min period. Blood glucose was clamped at the basal level (diabetic patients: 9.9±3.5, control subjects: 5.3±0.5 mmol/l) by a variable glucose infusion. Basal plasma insulin concentration was elevated in the diabetic patients (0.12±0.05 vs 0.05±0.02 pmol/ml, p<0.01). Insulin infusion resulted in comparable absolute increments in plasma insulin concentrations in the diabetic group and in the control group (0.44±0.13 vs 0.36±0.07 pmol/ml, NS). The metabolic clearance rate of glucose during the last 30 min of insulin infusion was lower in the diabetic patients (155±62 vs 320±69 ml·min^–1·m², p<0.01), reflecting peripheral insulin resistance. The decline in sodium clearance during insulin infusion was similar in diabetic subjects (1.8±1.1 vs 0.7±0.4 ml·min^–1·1.73 m^–2, p< 0.01) and in control subjects (1.7±0.3 vs 0.8±0.3 ml · min^–1 · 1.73 m^–2, p<0.01). The glomerular filtration rate and lithium clearance was unchanged, consequently calculated distal tubular fractional sodium reabsorption increased (diabetic patients: 92.9±4.1 vs 97.1±1.5, p<0.01, control subjects: 93.1±1.1 vs 96.5±0.6%, p< 0.01). Estimated extracellular fluid volume was 10% higher in the diabetic subjects (16.3±2.1 vs 14.8±2.01·1.73 m^–2, NS). In conclusion, the sodium retaining effect of insulin is preserved in Type 2 diabetic patients with peripheral insulin resistance. Insulin may contribute to sodium and fluid retention and thus to the increased frequency of hypertension in hyperinsulinaemic Type 2 diabetic patients.     

High-sensitivity C-reactive protein and impaired coronary vasoreactivity in young men with uncomplicated type 1 diabetes

Aims/hypothesis Elevated high-sensitivity C-reactive protein (hsCRP) concentrations indicate increased risk of future coronary events. The association between hsCRP and coronary vasoreactivity has not yet been examined in type 1 diabetic subjects.Methods We studied 18 young men who were non-smokers and who had uncomplicated type 1 diabetes. The diabetic subjects were divided into two groups, according to their median hsCRP concentration, as follows: (i) subjects with slightly elevated hsCRP (median 0.76 mg/l, range 0.47–4.73 mg/l, n=8); and (ii) subjects with low hsCRP (median 0.32 mg/l, range 0.11–0.35 mg/l, n=10). In addition we investigated 22 non-diabetic age-matched subjects (hsCRP: median 0.42 mg/l, range 0.11–1.31 mg/l). Resting myocardial blood flow and hyperaemic adenosine-stimulated flow during euglycaemic–hyperinsulinaemic clamp were determined using positron emission tomography and oxygen-¹⁵-labelled water.Results Diabetic subjects with slightly elevated hsCRP had significantly higher hsCRP concentrations than non-diabetic subjects (p=0.008). Resting myocardial blood flow was similar (NS) in diabetic subjects with slightly elevated hsCRP (0.79±0.19 ml·g^–1·min^–1) or low hsCRP (0.81±0.15 ml·g^–1·min^–1) and non-diabetic subjects (0.80±0.19 ml·g^–1·min^–1). Adenosine infusion induced a significant increase in blood flow in all study subjects (p<0.001) but was blunted in diabetic subjects with slightly elevated hsCRP (3.42±0.61 ml·g^–1·min^–1) when compared with diabetic subjects with low hsCRP (5.08±1.65 ml·g^–1·min^–1, p=0.02) or non-diabetic subjects (4.51±1.36 ml·g^–1·min^–1, p=0.04). Adenosine-stimulated flow was inversely correlated with hsCRP concentrations in all diabetic subjects (r=–0.70, p=0.001).Conclusions/interpretation In young subjects with uncomplicated type 1 diabetes, even slightly elevated hsCRP concentrations are associated with reduced coronary vasoreactivity.     

Early glomerular hyperfiltration and the development of late nephropathy in Type 1 (insulin-dependent) diabetes mellitus

Summary We performed a follow-up study of the glomerular function in a series of 29 Type 1 (insulin-dependent) diabetic patients who had been studied 18 years previously. Initial median duration of diabetes was 2 years (range 0–9) and at follow-up 21 (17–27) years. At follow-up, 8 diabetic patients exhibited increased urinary albumin excretion rate 515 (32-3234) g/min with glomerular filtration rates significantly lower than 21 diabetic patients with normal urinary albumin excretion (85 vs 126ml/min/1.73 m²; p<0.01). The patients with increased urinary albumin excretion rate also had higher arterial blood pressure (145/90 vs 120/80) mm Hg; p<0.02) and increased frequency of proliferative retinopathy (7 out of 8 vs 2 out of 21; p = 0.0001) as compared to the group with normal urinary albumin excretion. However, we found no association of increased urinary albumin excretion rate (incipient or overt nephropathy) to early glomerular hyperfiltration as median initial glomerular filtration rate was 142 ml/min/1.73 m² in the diabetic patients with increased urinary albumin excretion and 147 ml/min/1.73 m² in the patients with normal excretion rate (p>0.05)     

The activity of the renin-angiotensin-aldosterone system before and during submaximal bicycle exercise in relation to circulatory catecholamines in patients with Type 1 (insulin-dependent) diabetes mellitus

Summary To evaluate the renin-angiotensin-aldosterone system in relation to circulatory catecholamines, we determined renin activity, angiotensin II, aldosterone, adrenaline, and noradrenaline in plasma before and during a submaximal bicycle exercise test in 23 Type 1 (insulin-dependent) diabetic patients (aged 19–57 years, mean 37; duration of diabetes 2–32 years, mean 16), 17 with signs of cardiac autonomic neuropathy, and in 18 healthy non-diabetic subjects (aged 24–41 years, mean 29). At rest, Type 1 diabetic patients showed significantly lower aldosterone values than control subjects (0.14±0.02 nmol/l and 0.22±0.02 nmol/l; p<0.01) while renin activity (1.0±0.1 nmol·l^–1·h^–1 and 0.9±0.1 nmol·l^–1·h^–1) and angiotensin II (14±1 nmol/l and 18±2 nmol/l) did not differ significantly between patients and control subjects. During exercise, increments (increase from the resting value to the value at 80% of maximal working capacity) in renin (1.5±0.4 nmol·l^–1·h^–1 and 3.7±0.5 nmol·l^–1 ·h^–1; p<0.001), angiotensin II (28±8 nmol/l and 60±8 nmol/l; p<0.01), aldosterone (0.16±0.04 nmol/l and 0.25±0.05 nmol/l; p<0.05), adrenaline (1.96±0.49 nmol/l and 2.92±0.51 nmol/l; ps<0.05), and noradrenaline (12.01±1.25 nmol/l and 18.74±1.45 nmol/l; p<0.01) were significantly lower in the patients than in control subjects. There was no difference in the renin-angiotensin-aldosterone response to exercise between patients with and without cardiac autonomic neuropathy but the impaired catecholamine reaction was confined to patients with cardiac autonomic neuropathy. In conclusion, Type 1 diabetic patients demonstrated low resting plasma aldosterone and reduced increments in renin activity, angiotensin II, aldosterone, and catecholamines during exercise. The low aldosterone values might be related to dysfunction of adrenal zona glomerulosa cells while it is unlikely that the reduced response to exercise of the renin-angiotensin-aldosterone system simply reflects sympathetic nerve failure.     

Factors associated with basal metabolic rate in patients with Type 2 (non-insulin-dependent) diabetes mellitus

Summary To examine determinants of basal metabolic rate we studied 66 Type 2 (non-insulin-dependent) diabetic and 24 healthy age- and weight-matched control subjects with indirect calorimetry and infusion of [³H-3-] glucose. Eight Type 2 diabetic patients were re-studied after a period of insulin therapy. Basal metabolic rate was higher in Type 2 diabetic patients than in control subjects (102.8 ± 1.9 J · kg LBM^–1-min^–1 vs 90.7 ± 2.8 J · kg LBM^–1;min^–1; p<0.01) and decreased significantly with insulin therapy (p <0.01). The basal rate of hepatic glucose production was higher in Type 2 diabetic patients than in control subjects (1044.0 ± 29.9 vs 789.3 ± 41.7 mol/min; p <0.001) and decreased after insulin therapy (p <0.01). Hepatic glucose production correlated positively with basal metabolic rate both in Type 2 diabetic patients (r = 0.49; p <0.001) and in control subjects (r = 0.50; p<0.05). Lipid oxidation was increased in Type 2 diabetic patients compared with control subjects (1.68 ± 0.05 vs 1.37 ± 0.08 mol · kg LBM^–1 · min^–1'; p <0.01) and decreased significantly after insulin therapy (p <0.05). The rate of lipid oxidation correlated positively with basal metabolic rate both in Type 2 diabetic patients (r = 0.36; p <0.01) and in control subjects (r = 0.51; p <0.01). These data demonstrate that basal metabolic rate, rates of hepatic glucose production and lipid oxidation are interrelated in Type 2 diabetic patients. A reduction of the hepatic glucose production, however, is associated with a reduction in lipid oxidation, which in turn, may result in a reduction in basal metabolic rate.     

Diabetic background retinopathy is associated with impaired coronary vasoreactivity in people with Type 1 diabetes

Aims/hypothesis We examined whether diabetic background retinopathy is associated with reduced coronary vasoreactivity in people with Type 1 diabetes.Methods A total of 21 men with Type 1 diabetes were investigated, including 9 men with background retinopathy and 12 men without retinopathy. In addition, 12 non-diabetic, age-matched subjects were studied. All subjects were non-smokers, otherwise healthy and had no other diabetic complications. Resting myocardial blood flow and hyperaemic dipyridamole-stimulated flow (dipyridamole, 0.56 mg/kg during a 4-min period), a measure of coronary vasoreactivity, were measured during euglycaemic hyperinsulinaemic clamp (1 mU·kg^–1·min^–1) using positron emission tomography and oxygen-15-labelled water.Results Resting myocardial blood flow (0.82±0.13 vs 0.96±0.23 vs 0.88±0.25 ml·g^–1·min^–1, with vs without retinopathy vs non-diabetic subjects) and coronary vascular resistance (111.2±23.4 vs 95.5±15.8 vs 101.9±31.5 mmHg·min·g·ml^–1 respectively) were not significantly different between the groups. Dipyridamole infusion induced an increase in blood flow and a decrease in coronary vascular resistance in all study subjects (p<0.001). However, dipyridamole-stimulated flow and coronary vascular resistance were blunted in diabetic patients with retinopathy (2.9±0.9 ml·g^–1·min^–1 and 34.1±11.3 mmHg·min·g·ml^–1) when compared to diabetic patients without retinopathy (4.0±1.3 ml·g^–1·min^–1, p=0.04 and 24.6±7.5 mmHg·min·g·ml^–1, p=0.03) or non-diabetic subjects (4.5±1.4 ml·g^–1·min^–1, p=0.008 and 22.2±8.7 mmHg·min·g·ml^–1, p=0.01). Myocardial flow reserve was impaired in diabetic patients with retinopathy (3.6±1.0) when compared to non-diabetic subjects (5.3±1.9, p=0.02) but not significantly reduced when compared to diabetic patients without retinopathy (4.2±1.4, p=0.2).Conclusions/interpretation Diabetic background retinopathy appears to be associated with impaired coronary vasoreactivity in young people with Type 1 diabetes.Abbreviations PET positron emission tomography - [¹⁵O]H₂O oxygen-15-labelled waterJ. Sundell and T. Janatuinen contributed equally to this work     

Brain energy metabolism during hypoglycaemia in healthy and Type 1 diabetic subjects

Aims/hypothesis This study aimed to examine brain energy metabolism during moderate insulin-induced hypoglycaemia in Type 1 diabetic patients and healthy volunteers.Methods Type 1 diabetic patients (mean diabetes duration 13±2.5 years; HbA₁c 6.8±0.3%) and matched controls were studied before, during (0–120 min) and after (120–240 min) hypoglycaemic (~3.0 mmol/l) hyperinsulinaemic (1.5 mU·kg^–1·min^–1) clamp tests. Brain energy metabolism was assessed by in vivo ³¹P nuclear magnetic resonance spectroscopy of the occipital lobe (3 Tesla, 10-cm surface coil).Results During hypoglycaemia, the diabetic patients showed blunted endocrine counter-regulation. Throughout the study, the phosphocreatine:-ATP ratios were lower in the diabetic patients (baseline: controls 3.08±0.29 vs diabetic patients 2.65±0.43, p<0.01; hypoglycaemia: 2.97±0.38 vs 2.60±0.35, p<0.05; recovery: 3.01±0.28 vs 2.60±0.35, p<0.01). Intracellular pH increased in both groups, being higher in diabetic patients (7.096±0.010 vs. 7.107±0.015, p<0.04), whereas intracellular magnesium concentrations decreased in both groups (controls: 377±33 vs 321±39; diabetic patients: 388±47 vs 336±68 µmol/l; p<0.05).Conclusions/interpretation Despite a lower cerebral phosphocreatine:-ATP ratio in Type 1 diabetic patients at baseline, this ratio does not change in control or diabetic patients during modest hypoglycaemia. However, both groups exhibit subtle changes in intracellular pH and intracellular magnesium concentrations.Abbreviations [Mg²⁺]_i intracellular magnesium - NMR nuclear magnetic resonance - PCr phosphocreatine - pH_i intracellular pH - P_i intracellular inorganic phosphate     

Effects of lipase inhibition on gastric emptying of,and on the glycaemic,insulin and cardiovascular responses to,a high-fat/carbohydrate meal in type 2 diabetes

Aims/hypotheses We examined the effects of lipase inhibition with orlistat on (i) gastric emptying of, and (ii) the glycaemic, glucagon-like peptide-1 (GLP-1) and cardiovascular responses to, a high-fat/carbohydrate meal in type 2 diabetic patients.Methods Eight type 2 diabetic patients, who were aged 62 years (median range: 49–68 years) and managed by diet alone, consumed a meal containing 65 g powdered potato, 20 g glucose reconstituted with 200 ml water (labelled with 20 MBq ^99mTc-sulphur-colloid) and 45 g margarine. They did this on two separate occasions, with and without 120 mg orlistat, and while in the seated position with their back against a gamma camera. Venous blood samples for measurement of blood glucose, plasma insulin and GLP-1 were obtained immediately before the meal and at regular intervals afterwards. Blood pressure (systolic and diastolic) and heart rate were measured using an automated device.Results Gastric emptying of the meal was faster after orlistat than without orlistat (50% emptying time [mean ± SEM], 61±8 min vs 98±5 min; p=0.0001). In the first 60 min after the meal blood glucose (p=0.001) and plasma insulin (p=0.01) concentrations were higher in patients who had taken orlistat; between 60 and 180 min plasma GLP-1 (p=0.02) concentrations were lower after orlistat than without orlistat. Between 0 and 30 min systolic blood pressure (p=0.003) was lower, and heart rate (p=0.03) greater in subjects who had taken orlistat than in those who had not.Conclusions/interpretation Inhibition of fat digestion by orlistat may—as a result of more rapid gastric emptying—exacerbate postprandial glycaemia and the postprandial fall in blood pressure in patients with type 2 diabetes after ingestion of meals containing fat and carbohydrate.Conflict of Interest: None of the authors have a conflict of interest in relation to this study.     

The relationship between dysglycaemia and cardiovascular and renal risk in diabetic and non-diabetic participants in the HOPE study: a prospective epidemiological analysis

Aims/hypothesis Emerging data suggest that different indices of glycaemia are risk factors for clinical events. The aim of this analysis was to investigate the relationship between fasting plasma glucose or glycated haemoglobin (GHb) levels and incident cardiovascular (CV) outcomes, death, heart failure and overt nephropathy in diabetic and non-diabetic individuals enrolled in the Heart Outcomes Prevention Evaluation (HOPE) study.Materials and methods The adjusted 4.5-year risk of CV events (myocardial infarction or stroke or CV death), heart failure, death and overt nephropathy was analysed in relation to baseline and updated GHb levels (in 3,529 diabetic HOPE study participants) and baseline fasting plasma glucose levels (in 1,937 non-diabetic and 1,013 diabetic participants).Results In diabetic participants, a 1% absolute rise in the updated GHb predicted future CV events (relative risk [RR]=1.07, 95% CI 1.01–1.13; p=0.014), death (RR=1.12, 95% CI 1.05–1.19; p=0.0004), heart failure (RR=1.20, 95% CI 1.08–1.33; p=0.0008) and overt nephropathy (RR=1.26, 95% CI 1.17–1.36; p<0.0001) after adjusting for age, sex, diabetes duration, blood pressure, WHR, hyperlipidaemia and ramipril. Similarly, a 1 mmol/l rise in fasting plasma glucose was related to an increased risk of CV outcomes (RR=1.09, 95% CI 1.05–1.13; p<0.0001), death (RR=1.06, 95% CI 1.01–1.12; p=0.017), heart failure (RR=1.16, 95% CI 1.06–1.13; p=0.0007) and overt nephropathy (RR=1.34, 95% CI 1.23–1.45; p<0.0001) in the group composed of diabetic and non-diabetic individuals. The significant relationship between fasting plasma glucose and CV outcomes persisted after adjustment for diabetes status (RR=1.06, 95% CI 1.00–1.12; p=0.043).Conclusions/interpretation There is an independent progressive relationship between indices of glycaemia and incident CV events, renal disease and death. Clinical trials of glucose lowering to prevent these outcomes in diabetic and non-diabetic individuals are indicated.Listed by country in References 13 and 15.     

Diabetic nephropathy is associated with low-grade inflammation in Type 1 diabetic patients

Aims/hypothesis Increased concentrations of C-reactive protein and interleukin-6, a finding suggestive of the presence of inflammation, have been observed in Type 2 diabetes. In such patients, C-reactive protein was predictive of diabetic nephropathy. Studies on low-grade inflammatory markers and nephropathy in Type 1 diabetic patients have shown conflicting results. Therefore we studied whether low-grade inflammation is associated with diabetic nephropathy in Type 1 diabetic patients.Methods We divided 194 Type 1 diabetic patients into three groups from the Finnish Diabetic Nephropathy Study based upon their albumin excretion rate. Patients with normoalbuminuria (n=67) had no antihypertensive medication or signs of cardiovascular disease, while patients with microalbuminuria (n=64) or macroalbuminuria (n=63) were all treated with an angiotensin-converting enzyme inhibitor, a drug that could attenuate low-grade inflammation. As a measure of insulin sensitivity we used estimated glucose disposal rate. C-reactive protein was measured by radioimmunoassay and interleukin-6 by high sensitivity enzyme immunoassay.Results C-reactive protein was higher in micro- and macroalbuminuric patients compared to normoalbuminuric patients (normoalbuminuria 2.0±1.7, microalbuminuria 2.6±1.7, macroalbuminuria 2.9±2.5 mg/l; p=0.016), while interleukin-6 increased in parallel with the severity of the renal disease (1.9±1.5, 2.9±3.3, 3.6±3.1 ng/l; p<0.0001). In multiple regression analysis albumin excretion rate was the only variable independently associated with C-reactive protein (p=0.03), whereas albumin excretion rate (p=0.0003), HDL-cholesterol (p=0.0135) and duration of diabetes (p=0.0176) were independently associated with interleukin-6.Conclusions/interpretation Low-grade inflammatory markers are associated with diabetic nephropathy in Type 1 diabetic patients. The predictive value needs to be assessed.Abbreviations DN diabetic nephropathy - CRP C-reactive protein - eGDR estimated glucose disposal rate - FinnDiane finnish diabetic nephropathy study - MDRD modification of diet in renal disease     

Lipids and diabetic nephropathy: hypertension,microalbuminuria and lipids in type 2 diabetic patients

Hypertension and microalbuminuria are predictors of cardiovascular mortality in type 2 (non-insulin-dependent) diabetes independently of other conventional risk factors. The presence of high triglyceride levels with small and/or dense low density lipoprotein particles is associated with cardiovascular disease. The aim of this study was to analyse the plasma lipids, Na⁺/Li⁺ countertransport (a genetic marker of hypertension) and microalbuminuria in type 2 diabetic patients. Plasma lipids were determined in 15 normotensive normoalbuminuric (H^–M^–), 32 hypertensive normoalbuminuric (H⁺M^–) and 22 hypertensive microalbuminuric (H⁺M⁺) type 2 diabetic patients and in 20 sex-and age-matched non-diabetic subjects. Plasma cholesterol was significantly higher in H⁺M⁺ patients than in controls (226±38 vs 192±38 mg/dl, mean ±SD). Plasma triglycerides were significantly higher in H⁺M⁺ patients than in either controls or H^–M^– patients (192±117 vs 104±59 and 115±52 respectively). The Na⁺/Li⁺ countertransport activity in red blood cells was significantly higher in H⁺M^– and H⁺M⁺ patients than in controls, and in the type 2 diabetic patients it was directly related to plasma triglycerides (r=0.53,P<0.0001) and inversely to high density lipoprotein (HDL) cholesterol (r=–0.43,P<0.0001). Microalbuminuria, hypertension and elevated Na⁺/Li⁺ countertransport activity are thus associated with high triglyceride and low HDL cholesterol levels in type 2 diabetic patients. This atherogenic lipoprotein pattern might at least partially explain the association of microalbuminuria with cardiovascular disease in type 2 diabetes.     

Sustained reduction of proteinuria in Type 2 (non-insulin-dependent) diabetes following diet-induced reduction of hyperglycaemia

Summary To determine whether sustained control of hyperglycaemia in Type 2 (non-insulin-dependent) diabetic patients would diminish proteinuria, the effect of hypocaloric diet therapy (500 kcal/day) on proteinuria was assessed in obese, Type 2 diabetic patients (n=24) and compared with results obtained for obese subjects with normal glucose tolerance (n=7) and impaired glucose tolerance (n=6). Diet therapy of similar mean duration resulted in similar percentage weight loss (mean percentage of original weight ±SEM) in diabetic (13.6±1.6%), glucose intolerant (16.4±3.3%) and obese nondiabetic (11.0±1.0%) subjects. Following therapy, plasma glucose concentrations 2h after an oral glucose load declined in the diabetic (18.34±0.81 to 10.67±0.50 mmol/1, mean ±SEM; p<0.001) and in the glucose intolerant subjects (10.2±0.3 to 7.3±0.4 mmol/l, p<0.01) while remaining unchanged in the obese non-diabetic subjects (7.09±0.23 to 6.77±0.32 mmol/l, NS). Concentrations of total protein of plasma origin and albumin in 24-h urine collections were quantified by a sensitive immunonephelometric assay using specific antisera. Initially, 24-h excretion of total protein and albumin were elevated in the diabetic [mg protein/24 h; (median±95% confidence limits): 63 (42–138), p<0.05; albumin: 26 (14–56), p<0.05] and glucose intolerant subjects [protein:52 (13–92), NS; albumin: 24 (3–61), NS] compared with the non-diabetic subjects [protein: 20 (5–38); albumin: 6.2 (3.5–9.5)]. Following diet therapy, both total protein and albumin excretion were reduced significantly in diabetic subjects (p<0.001) and similar decreases were observed in clearance rates of protein and albumin. Initially, 11 out of the 24 diabetic subjects had 24-h albumin excretion in the subclinical range (>30, < 500 mg/24h), whereas following diet therapy, only three out of the 11 had subclinical albuminuria. For all subjects, the decrease in albumin excretion following diet therapy was significantly correlated with the initial albumin excretion (r=0.63, p<0.0001). In one diabetic subject, whose glucose tolerance and albumin excretion were sequentially monitored for 14 months, the decreases in glycaemia and proteinuria observed in the first month of therapy persisted after discontinuation of diet therapy. Thus, metabolic control of Type2 diabetes by a hypocaloric diet produced significant sustained reductions in proteinuria. The question remains whether or not this retards the development of clinical nephropathy or end stage renal disease.