Christian Berne

A Comparison of the Effects of Hydrochlorothiazide and Captopril on Glucose and Lipid Metabolism in Patients with Hypertension

It has been suggested that the metabolic side effects of antihypertensive drugs are responsible for their failure to reduce cardiovascular morbidity in patients with hypertension. Therefore, in 50 patients with essential hypertension, we performed a randomized, double-blind, crossover study comparing the effects of carbohydrate and lipid metabolism of captopril (mean [+/- SD] dose, 81 +/- 24 mg per day) and hydrochlorothiazide (40 +/- 12 mg per day) over two four-month treatment periods. Captopril increased the insulin-mediated disposal of glucose, as compared with placebo, from 5.7 +/- 2.4 to 6.3 +/- 2.5 mg per kilogram of body weight per minute (P less than 0.05), whereas hydrochlorothiazide caused a decrease from 6.4 +/- 2.0 to 5.7 +/- 1.9 (P less than 0.01). Captopril had no effect on the basal insulin concentration, but it decreased the late (30- to 90-minute) insulin response to glucose and increased the early (2- to 6-minute) insulin peak. Hydrochlorothiazide increased the basal insulin concentration and the late insulin response to glucose. These findings may be explained by an increase in insulin sensitivity with captopril and a decrease with hydrochlorothiazide. Little or no change was seen in serum lipid or lipoprotein levels during treatment with captopril, whereas hydrochlorothiazide caused significant increases in serum total (5 percent) and low-density lipoprotein (6 percent) cholesterol levels and total (15 percent) and very-low-density lipoprotein (25 percent) triglyceride levels, as compared with placebo (P less than 0.01 for all comparisons). We conclude that hydrochlorothiazide for the treatment of essential hypertension has adverse effects on glucose and lipid metabolism. It is possible, but not proved in this study, that these changes may contribute to the risk for diabetes mellitus and coronary heart disease. In contrast, captopril appears to have beneficial or no effects on glucose and lipid metabolism.

Insulin resistance is a characteristic feature of primary hypertension independent of obesity

The relationship between abnormalities in carbohydrate metabolism and hypertension was studied in 143 newly detected hypertensive patients (59% obese) of both sexes (90 males, 53 females) and compared with 51 normotensive controls. Insulin-mediated glucose disposal assessed with the euglycemic insulin clamp technique was significantly decreased in both non-obese (7.2 +/- 2.1 mg/kg/min; P less than .05) and obese hypertensives (5.1 +/- 2.1 mg/kg/min; P less than .01) compared with the controls (8.4 +/- 1.8 mg/kg/min). The decrease in insulin sensitivity and increase in basal insulin as well as a decreased rate of glucose disposal after an intravenous glucose tolerance test (IVGTT) were verified also after statistical adjustment for sex, age, body mass index, and waist-hip ratio. The insulin index (ratio between peak and basal insulin) during IVGTT was significantly decreased in the hypertensive patients (P less than .001). After the statistical adjustment for the factors mentioned the following lipid abnormalities were still significant: total cholesterol (6.25 +/- 1.12 mmol/L non-obese; 6.06 +/- 1.20 mmol/L obese; 5.41 +/- 1.02 mmol/L controls), triglycerides (1.70 +/- 0.74 mmol/L nonobese; 2.26 +/- 1.13 mmol/L obese; 1.24 +/- 0.53 mmol/L controls) and free fatty acids (0.57 +/- 0.20 mmol/L nonobese; 0.59 +/- 0.20 mmol/L obese; 0.48 +/- 0.15 mmol/L controls). This study shows that after correction for a series of probable confounding variables, hypertension emerges as part of a syndrome characterized by major abnormalities of carbohydrate, insulin, and lipid metabolism, which independently or in concert may act as important risk factors for cardiovascular disease.

Production of tissue factor by pancreatic islet cells as a trigger of detrimental thrombotic reactions in clinical islet transplantation

BACKGROUND Intraportal transplantation of pancreatic islets offers improved glycaemic control and insulin independence in type 1 diabetes mellitus, but intraportal thrombosis remains a possible complication. The thrombotic reaction may explain why graft loss occurs and islets from more than one donor are needed, since contact between human islets and ABO-compatible blood in vitro triggers a thrombotic reaction that damages the islets. We investigated the possible mechanism and treatment of such thrombotic reactions. METHODS Coagulation activation and islet damage were monitored in four patients undergoing clinical islet transplantation according to a modified Edmonton protocol. Expression of tissue factor (TF) in the islet preparations was investigated by immunohistochemistry, immunoprecipitation, electron microscopy, and RT-PCR. To assess TF activity in purified islets, human islets were mixed with non-anticoagulated ABO-compatible blood in tubing loops coated with heparin. FINDINGS Coagulation activation and subsequent release of insulin were found consistently after clinical islet transplantation, even in the absence of signs of intraportal thrombosis. The endocrine, but not the exocrine, cells of the pancreas were found to synthesise and secrete active TF. The clotting reaction triggered by pancreatic islets in vitro could be abrogated by blocking the active site of TF with specific antibodies or site-inactivated factor VIIa, a candidate drug for inhibition of TF activity in vivo. INTERPRETATION Blockade of TF represents a new therapeutic approach that might increase the success of islet transplantation in patients with type 1 diabetes, in terms of both the risk of intraportal thrombosis and the need for islets from more than one donor.

Physiological Hyperglycemia Slows Gastric Emptying in Normal Subjects and Patients With Insulin-Dependent Diabetes Mellitus

BACKGROUND & AIMS Marked hyperglycemia slows and hypoglycemia accelerates gastric emptying. The aim of this study was to determine the effect of physiological changes in blood glucose gastric emptying. METHODS In 8 healthy subjects and 9 patients with insulin-dependent diabetes mellitus (IDDM) without gastrointestinal tract symptoms or evidence of neuropathy, gastric emptying of a mixed meal was measured by scintigraphy. Using an insulin-glucose clamp, the blood glucose concentration was stabilized at 4 and 8 mmol/L on 2 separate days. RESULTS The intragastric retention of the solid meal component at 100 minutes was 55.2% +/- 4.5% at 8 mmol/L vs. 36.7% +/- 5.5% at 4 mmol/L (P = 0.004) in normal subjects and 44.2% +/- 4.2% vs. 35.7% +/- 4.2% (P = 0.004) in patients with IDDM. The time taken for 50% emptying of the liquid meal was 57.0 +/- 10.8 minutes at 8 mmol/L vs. 32.2 +/- 12.6 minutes at 4 mmol/L (P = 0.002) in normal subjects and 41.3 +/- 3.4 minutes vs. 29.1 +/- 3.5 minutes (P = 0.002) in patients with IDDM. CONCLUSIONS Changes in blood glucose within the normal postprandial range have a significant impact on gastric emptying in both normal subjects and patients with IDDM.

Application of prazosin is associated with an increase of insulin sensitivity in obese patients with hypertension

SummaryThe aim of this study was to determine whether insulin sensitivity measured by the euglycaemic insulin clamp technique is lower in patients with primary hypertension than in matched healthy control subjects, and whether this sensitivity was affected after 12 weeks of antihypertensive treatment with the alpha 1-adrenoceptor blocking drug prazosin. Twelve moderately obese normoglycaemic patients (four men), with hypertension not previously treated with pharmacological agents and diastolic blood pressure above 100 mm Hg, and 12 healthy matched control subjects participated. Supine blood pressure decreased 12/5 mmHg (p<0.01) and standing blood pressure 14/9 mmHg (p=0.001) during prazosin treatment (mean dosage 5.3±1.6 mg/day (SD)). During euglycaemic insulin clamp studies the control subjects showed a higher mean glucose uptake than the untreated hypertensive patients (7.5±1.0 and 5.8±1.9 mg·kg b.w.−1·min−1, respectively, p<0.01). During prazosin treatment there was no significant difference between the hypertensive patients and the control subjects in this respect (6.6±2.8 and 7.5±1.0, respectively, p=0.21). During prazosin treatment, however, the disappearance rate of glucose decreased during the intravenous glucose tolerance test (from 1.7±0.9 to 1.3±0.6, p<0.02) and the area under the glucose concentration-time curve decreased by 38% (from 473±119 to 294±99, p<0.001). The peak insulin concentration decreased from 55±35 to 46±32 mU/l (p<0.006) and the area under the insulin concentration-time curve was suppressed by 38% (from 2368±1597 to 1479±940, p<0.01). This study shows that treatment of moderately obese hypertensive patients with prazosin is associated with an increase of the insulin-mediated glucose disposal and a decrease of the insulin response to an intravenous glucose load.

Cancer risk in patients with diabetes mellitus

Cancer incidence was ascertained in a population-based cohort of 51,008 patients in Uppsala, Sweden, who were given a discharge diagnosis of diabetes mellitus during 1965–83. Complete follow-up through 1984 with exclusion of the first year of observation showed that the observed number of cancers in females (1,294) was eight percent higher than expected (relative risk [RR]=1.1, 95 percent confidence interval =11.0–1.1), whereas in males the observed number (1,123) was close to the expected (RR=1.0, 0.9–1.1). Significantly increased risks of pancreatic (RR=1.4, 1.2–1.7), primary liver (RR=1.5, 1.2–1.7), and endometrial (RR=1.5, 1.2–1.8) cancers and a lower than expected number of prostatic cancers (RR=0.7, 0.7–09) were found in this cohort of diabetic patients. The excess risk of pancreatic cancer was similar in females and males and evident both during one through four years (RR=1.7, 1.4–2.1) and five through nine years (RR=1.3, 0.9−1.7) of follow-up, but not thereafter. A similar pattern was found for primary liver cancer, but the RRs were generally higher in males than in females.

Angiotensin II and the endocrine pancreas: effects on islet blood flow and insulin secretion in rats.

Summary An intrinsic angiotensin system has been described in the pancreas, with angiotensin II specific receptors being present on both exocrine, endocrine and vascular cells. The aim of the present study was to evaluate the effects of angiotensin II on insulin secretion and blood flow regulation in the pancreas. Blood flows were determined with a microsphere technique. Infusion of angiotensin II induced a dose-dependent reduction in both whole pancreatic and islet blood flow, which was most pronounced in the former. Administration of enalaprilate, an inhibitor of angiotensin-converting enzyme, and saralasin, a non-selective angiotensin II receptor antagonist, preferentially increased islet blood flow. The effects of angiotensin II on insulin release were examined by measuring insulin concentrations in the effluents from isolated perfused pancreata. In these preparations, enalaprilate affected neither basal nor glucose-stimulated insulin release, whereas angiotensin II delayed the first phase of insulin release in response to glucose. The effect of angiotensin II was probably due to initial marked vasoconstriction. The retardation of insulin release could be avoided by adding angiotensin II to the perfusion medium 20 min before glucose administration, i. e. so that the vasoconstriction had disappeared when glucose-stimulation began. The present study suggests that the angiotensin-system is important in regulation of islet blood flow and points to a pivotal role of islet blood perfusion for an adequate insulin release. [Diabetologia (1998) 41: 127–133]

Sleep-disordered breathing and glucose metabolism in hypertensive men: a population-based study.

Abstract. Elmasry A, Lindberg E, Berne C, Janson C, Gislason T, Awad Tageldin M, Boman G (Uppsala University, Akademiska Sjukhuset, Uppsala, Sweden; Ain Shams University, Cairo, Egypt; and Vifilsstadir Hospital, Gardabaer, Iceland). Sleep‐disordered breathing and glucose metabolism in hypertensive men: a population‐based study. J Intern Med 2001; 249: 153–161.

The sympathetic response to euglycaemic hyperinsulinaemia

SummarySympathetic nervous system activation by insulin has been suggested as a mechanism explaining the association between insulin resistance and hypertension. We further examined the effect of insulin by direct microneurographic muscle and skin nerve sympathetic activity recordings during euglycaemic insulin clamps in healthy subjects. The mean plasma insulin level was elevated from 5.3±0.7 to 92.2±2.2 mU/l in seven subjects during a 90-min one-step clamp. In six other subjects plasma insulin was further raised from 85.7±4.0 mU/l to 747±53 mU/l between 45–90 min (two-step clamp). Four of the latter subjects received a sham clamp with NaCl infusions only on a second recording session. At the low dose of insulin muscle nerve sympathetic activity increased from a resting level of 22.7±5.0 bursts per min to 27.7±5.0 bursts per min at 15 min (p<0.05). The increases in muscle nerve sympathetic activity were significant (p<0.001; ANOVA) throughout insulin infusion, with a slight further increase (from 29.2±1.6 to 32.3±1.9 bursts per min) at the supraphysiological insulin concentration. During sham clamps muscle nerve sympathetic activity did not increase. Both insulin clamps induced minor, but significant, increases in forearm venous plasma noradrenaline concentrations. Skin nerve sympathetic activity (n=3) did not change during insulin infusions. Heart rate increased slightly but significantly (p<0.005), during the insulin clamps. Blood pressure was not notably affected. In conclusion, hyperinsulinaemia was associated with increased vasoconstrictor nerve activity to skeletal muscle and with no change of sympathetic outflow to skin.

Serum lipoprotein lipid profile in women with the polycystic ovary syndrome: relation to anthropometric, endocrine and metabolic variables

OBJECTIVE Although often associated with insulin resistance and glucose intolerance, various lipoprotein abnormalities have been found in polycystic ovary syndrome (PCOS) but not Invariably so when the degree of obesity is taken into account. We have therefore Investigated the serum lipid profile in a group of women with polycystic ovary syndrome with and without obesity. DESIGN Cross‐sectional study of serum lipoprotein lipids and plasma free fatty acids in relation to anthropometric, metabolic and hormonal variables in women with PCOS and weight‐matched controls.