Dose-related antihypertensive effects of irbesartan in patients with mild-to-moderate hypertension

Two multicenter, double-blind, placebo-controlled, parallel group studies were conducted to evaluate the efficacy, safety, pharmacokinetics, and pharmacodynamics of the angiotensin II receptor (AT1 subtype) antagonist irbesartan. The effect of irbesartan withdrawal and the effect of adding hydrochlorothiazide (HCTZ) to irbesartan were also assessed. After a placebo lead-in phase, all patients were randomized to 8 weeks of double-blind therapy with either placebo (n = 158) or irbesartan at doses of 1, 5, 10, 25, 50, 100, 200, or 300 mg (n = 731 total) orally once daily. Irbesartan reduced blood pressure in a dose-related manner. Reductions from baseline in trough seated diastolic blood pressure ranged from 7.5 mm Hg for 50 mg irbesartan to 11.6 mm Hg for 300 mg irbesartan. At week 8, statistically significant reductions over placebo were observed in trough seated blood pressure with all irbesartan doses > or = 50 mg. These reductions reached statistical significance versus placebo within 2 weeks with 100, 200, and 300 mg irbesartan. Plasma irbesartan concentrations correlated with dose. Angiotensin II and aldosterone levels generally showed dose-related changes, consistent with AT1 receptor blockade. In patients not controlled at 8 weeks, the addition of 12.5 mg HCTZ resulted in further dose-related reductions in blood pressure. Irbesartan demonstrated a placebo-like safety profile and no dose-related toxicity. Irbesartan, administered alone or in combination with HCTZ, was well tolerated. Withdrawal of irbesartan did not result in rebound hypertension or adverse events. Thus, once-daily irbesartan is both an effective and safe antihypertensive agent for the treatment of mild-to-moderate hypertension.

Effect of troglitazone in insulin-treated patients with type II diabetes mellitus. Troglitazone and Exogenous Insulin Study Group

BACKGROUND

Troglitazone is a new oral antidiabetic drug that increases the sensitivity of peripheral tissues to insulin. It may therefore increase the efficacy of exogenous insulin in patients with insulin-resistant diabetes mellitus.

METHODS

We studied the effect of troglitazone or placebo in 350 patients with poorly controlled non-insulin-dependent (type 2) diabetes mellitus (glycosylated hemoglobin values, 8 to 12 percent; normal, 4.3 to 6.1 percent) despite therapy with at least 30 U of insulin daily. The patients were randomly assigned to receive 200 mg of troglitazone (116 patients), 600 mg of troglitazone (116 patients), or placebo (118 patients) daily for 26 weeks. Insulin doses were not increased and were reduced only to prevent hypoglycemia. Glycosylated hemoglobin, serum glucose while fasting, serum total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and triglycerides were measured 5 times during an 8-week base-line period and 10 times during the 26-week treatment period. Daily insulin doses were recorded during both periods.

RESULTS

Ninety percent of the patients completed the study. The adjusted mean glycosylated hemoglobin values decreased by 0.8 and 1.4 percentage points, respectively, in the group given 200 mg of troglitazone and the group given 600 mg of troglitazone, and fasting serum glucose concentrations decreased by 35 and 49 mg per deciliter (1.9 and 2.7 mmol per liter), respectively, despite decreases in the insulin dose of 11 percent and 29 percent (P<0.001 for all comparisons with the placebo group). Serum total cholesterol, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol concentrations increased slightly and serum triglyceride concentrations decreased slightly in the troglitazone-treated patients.

CONCLUSIONS

When given in conjunction with insulin, troglitazone improves glycemic control in patients with type 2 diabetes mellitus.

Effects of a large supper on glucose levels the following morning in patients with type 2 diabetes

Seventeen patients were studied to test the hypothesis that a large evening meal influences the fasting glucose level and glucose tolerance the following morning in patients with type 2 diabetes. Oral hypoglycemic agents were discontinued for 2 weeks. The baseline fasting plasma glucose levels were 12.3 +/- 0.9 mmol/L. Fasting and postprandial (post-Sustacal) glucose, insulin, and C-peptide measurements were performed the morning after the patients received three separate meal protocols spaced 1 week apart. The caloric distribution of the meal protocols was (1) 7 kcal/kg of ideal body weight breakfast and lunch and 14 kcal/kg supper (small supper); (2) 7 kcal/kg breakfast and lunch and 28 kcal/kg for supper (large supper); and (3) 14 kcal/kg breakfast and lunch (no supper). Fasting glucose level were higher the morning after the large supper compared to no supper (13.6 +/- 0.7 versus 12.3 +/- 0.5 mmol/L, p < 0.05) and also to the small supper (13.6 +/- 0.7 versus 12.5 +/- 0.6 mmol/L, p = 0.05). No difference was observed in the fasting glucose levels between the small supper and no supper (p > 0.2). The fasting insulin and C-peptide levels, and the post-Sustacal areas under the curve of glucose, insulin, and C-peptide did not differ among the meals. In patients with type 2 diabetes, a large evening meal is associated with a modest elevation in fasting glucose the following morning.

Glycemic control and cardiopulmonary function in patients with insulin-dependent diabetes mellitus

BACKGROUND

We studied cardiopulmonary function during exercise in young subjects with long-standing insulin-dependent diabetes mellitus (IDDM) who have no clinical cardiopulmonary disease to determine the relationships of aerobic capacity, gas exchange, ventilatory power requirement, and cardiac output to chronic glycemic control.

METHODS

Eighteen subjects with IDDM and 14 normal control subjects were studied. Nine diabetic subjects received twice daily insulin injections and had chronically elevated levels of glycosylated hemoglobin (hyperglycemic group); 9 other diabetic subjects received insulin via continuous infusion pumps and maintained chronic near-normal levels of glycosylated hemoglobin (normoglycemic group). At the end of at least 7 years of regular follow-up, aerobic capacity was determined by cycle ergometry. Lung volume, diffusing capacity, and cardiac output during exercise were measured by a rebreathing technique. Ventilatory power was measured by the esophageal balloon technique.

RESULTS

Maximal work load and oxygen uptake were markedly impaired in chronically hyperglycemic diabetic patients associated with significant restrictions of lung volume, lung diffusing capacity, and stroke index during exercise. Membrane diffusing capacity was significantly reduced at a given cardiac index. The normoglycemic patients consistently showed less impairment than the hyperglycemic patients.

CONCLUSION

Physiologically significant cardiopulmonary dysfunction develops in asymptomatic patients with long-standing IDDM. Chronic maintenance of near-normoglycemia is associated with improved cardiopulmonary function.

A double-masked placebo-controlled trial assessing effects of various doses of BTS 67,582, a novel insulinotropic agent, on fasting hyperglycemia in NIDDM patients

OBJECTIVE

To determine the effect over a 4-week period of varying doses of BTS 67,582, a novel nonsulfonylurea insulinotropic agent, on fasting plasma glucose (FPG) levels in sulfonylurea-responsive NIDDM patients.

RESEARCH DESIGN AND METHODS

This was a 12-week multicenter, double-masked, placebo-controlled trial. Patients entered a 4-week stabilization period during which they received their previously prescribed sulfonylurea. Qualified patients (FPG < or = 10 mmol/l) then entered a 4-week sulfonylurea withdrawal single-masked placebo run-in period. Qualified patients (FPG 8.9-16.7 mmol/l) were randomized to either placebo (n = 14), 50 mg b.i.d. BTS 67,582 (n = 18), 250 mg b.i.d. BTS 67,582 (n = 18), 500 mg b.i.d. BTS 67,582 (n = 15), 100 mg q.d. BTS 67,582 (n = 17), or 500 mg q.d. BTS 67,582 (n = 16). The primary efficacy variables were mean changes from baseline in FPG and fructosamine (FRUC). Additional variables included mean changes from baseline in HbA1c, fasting serum insulin (FSI), and fasting serum C-peptide.

RESULTS

After 4 weeks of treatment, all BTS 67,582 dose groups showed a decrease from baseline in FPG and FRUC compared with the placebo group. The treatment groups of 250 mg b.i.d. (-3.1 +/- 0.7 mmol/l), 500 mg b.i.d. (-2.3 +/- 0.6 mmol/l), and 500 mg q.d. (-1.2 +/- 0.7 mmol/l) had statistically significant (P < 0.05) decreases in FPG compared with placebo (0.7 +/- 0.6 mmol/l). Similarly, there were statistically significant (P < 0.05) decreases from baseline in FRUC for the 250 mg b.i.d (-55 +/- 10 mumol/l), 500 mg b.i.d. (-40 +/- 12 mumol/l), and 500 mg q.d. (-13 +/- 9 mumol/l) treatment groups compared with placebo (15 +/- 11 mumol/l). Although the treatment period was only 4 weeks in duration, there were also significant differences (P < 0.05) in the HbA1c changes from baseline for the 250 mg b.i.d. (0.0 +/- 0.1%) and 500 mg b.i.d. (-0.2 +/- 0.1%) treatment groups compared with placebo (0.6 +/- 0.2%). There were no significant differences among the treatment groups in the changes from baseline for FSI or C-peptide levels. The most frequently reported side effects were headache, asthenia, infection, and thirst, and the incidence of these events as well as the incidence of study drug discontinuation was comparable in all treatment groups including placebo.

CONCLUSIONS

Four weeks of treatment with BTS 67,582 at doses of 250 mg b.i.d. and 500 mg b.i.d. in NIDDM patients was effective in reducing FPG and FRUC, with significant results also seen for HbA1c. The drug was well tolerated with an incidence of discontinuations and laboratory side-effect safety profiles comparable to placebo. BTS 67,582 is a safe and effective oral treatment for NIDDM patients.

Essential hypertension is associated with decreased insulin clearance and insulin resistance

Essential hypertension is associated with multiple metabolic abnormalities, among them, hyperinsulinemia. This hyperinsulinemia is attributed to the presence of decreased insulin sensitivity (insulin resistance) with consequent compensatory insulin secretion. We tested the hypothesis that decreased insulin clearance is present in hypertensive subjects and contributes to hyperinsulinemia independently of the degree of insulin resistance. Seventy-five subjects were studied (48 hypertensive and 27 normotensive). Both groups were comparable in terms of age, body fat content, waist-to-hip ratio, and sex distribution. A primed continuous insulin infusion at 40 mU/m2 per minute was performed. Glucose was maintained at baseline levels with the euglycemic clamp technique. Hypertensive subjects were characterized by decreased insulin sensitivity (insulin-mediated glucose uptake: 5.14 +/- 0.28 versus 7.26 +/- 0.61 mg glucose/kg fat-free mass per minute, hypertensive versus normotensive, P = .002), increased insulin levels during the insulin infusions (804 +/- 36 versus 510 +/- 38 pmol/L, hypertensive versus normotensive, P < .001), and decreased insulin metabolic clearance rate (328 +/- 15 versus 521 +/- 30 mL/min per meter squared, hypertensive versus normotensive, P < .001). In an ANCOVA (including sex, degree of obesity, waist-to-hip ratio, and insulin sensitivity as covariates) the differences in insulin metabolic clearance rate between normotensive and hypertensive subjects remained highly significant (P < .001). Insulin metabolic clearance rate was significantly associated with fasting insulin levels. We conclude that essential hypertension is independently associated with decreased insulin metabolic clearance rate in addition to insulin resistance. A low insulin metabolic clearance rate may be a contributory factor to the hyperinsulinemia observed in essential hypertension.

Relationship between insulin sensitivity, hyperinsulinemia, and insulin-mediated sympathetic activation in normotensive and hypertensive subjects

The adrenergic response to high physiological hyperinsulinemia was studied in 39 hypertensive subjects (28 men and 11 women) and 25 normal volunteers (15 men and 10 women), using the euglycemic clamp technique. Control studies using 0.45% saline infusions (sham studies) were also performed. Before and during the clamp procedure, plasma norepinephrine (NE) and epinephrine (E) were measured using a high performance liquid chromatographic method (HPLC). The association between the increment in NE and E levels and insulin sensitivity, steady-state insulin level during the clamps, waist to hip ratio (WHR), baseline NE levels and gender was studied. NE levels increased during the hyperinsulinemic period (mean increase 46 +/- 6 pmol P < .001 upsilon baseline and P < .01 upsilon sham studies). E levels did not differ between the insulin clamps and the sham studies. Insulin sensitivity was not significantly associated with the increment in NE. Hypertensive subjects had a higher NE increase than the normotensive individuals (55 +/- 7 upsilon 30 +/- 10 pmol, P = .03), but also had higher insulin levels during the clamps (839 +/- 43 upsilon 522 +/- 38 pmol, P < .001). Insulin levels accounted for most of the differences in NE increase between the normotensive and hypertensive groups. Gender, adiposity and WHR were also associated with NE increment. We conclude that the insulin mediated sympathetic activation is not affected in the presence of decreased insulin sensitivity for glucose utilization. The greater degree of sympathetic activation observed in hypertensive subjects is a function of the level of insulinemia obtained during the clamps.

Hypertension in diabetes mellitus

Hypertension should be detected and treated early in diabetic patients. It has a marked contribution to the morbidity and mortality of diabetic individuals due to both atherosclerosis and microvascular disease. Antihypertensive treatment is an effective tool in slowing the progression of early and advanced diabetic nephropathy. Prospective studies addressing the effects of antihypertensive regimens on the incidence of CHF, stroke, and coronary artery disease in the diabetic population are not available. We assume that the beneficial effects of therapy apply to both diabetic and nondiabetic subjects. Glycemic control and the lipid profile are major concerns when selecting an antihypertensive drug. Because hyperinsulinemia and insulin resistance have been advocated as hypertensive and atherosclerotic risk factors, the effects of antihypertensive drugs on insulin action and plasma insulin levels may also become an important element in the selection of an antihypertensive agent. ACE inhibitors, calcium channel blockers, and alpha-adrenergic blockers probably offer the most favorable metabolic profile when compared with diuretics and beta-blockers and should be used as the initial drugs in most clinical settings.

Efficacy and safety of pravastatin in the treatment of patients with type I or type II diabetes mellitus and hypercholesterolemia

PURPOSE

Patients with type I and type II diabetes mellitus have an increased risk of coronary heart disease. In many diabetics, hypercholesterolemia is present and further exacerbates this risk. We investigated the efficacy and safety of pravastatin in the treatment of patients with type I or type II diabetes mellitus and hypercholesterolemia.

PATIENTS AND METHODS

In this 24-week, multi-center, double-blind, placebo-controlled study, 94 patients (45 men, 49 women), 18 to 70 years of age, with type I or type II diabetes mellitus and hypercholesterolemia (fasting plasma low-density lipoprotein cholesterol [LDL-C] levels > 150 mg/dL and above the 75th percentile for the US population by age and gender) were randomized to receive pravastatin 20 mg hs or matching placebo. Two patients were randomized to treatment with drug for every 1 randomized to placebo. The dose could be doubled after 10 weeks, and cholestyramine or colestipol could be added after 18 weeks, as needed, to attempt to lower the LDL-C levels to below the 50th percentile for the US population.

RESULTS

Significant reductions in LDL-C (-27.6%), total cholesterol (-22.1%), very-low-density lipoprotein cholesterol (-22.6%), and triglycerides (-12.8%) (P < or = 0.001 versus placebo for all reductions), and significant increases in high-density lipoprotein cholesterol (4.4%) (P < or = 0.05 versus placebo) were noted in the pravastatin treatment group (average dose 29.5 mg) at 16 weeks. The beneficial lipid-lowering effects of pravastatin were maintained throughout the 24 weeks of the study. Pravastatin was well tolerated, and the frequency of side effects was similar in the pravastatin and placebo groups. No clinically significant changes in the control of diabetes, as assessed by fasting blood glucose levels and glycosylated hemoglobin measurements, were seen during this study.

CONCLUSION

The results of this study demonstrate that pravastatin is well tolerated and effective in lowering total cholesterol and LDL-C in patients with type I or type II diabetes mellitus and hypercholesterolemia.

Kinetics of glucose delivery to subcutaneous tissue in rats measured with 0.3-mm amperometric microsensors

The time between intravenous injection of a glucose bolus and the time the glucose concentration peaked in the subcutaneous tissue was measured in pentobarbital-anesthetized rats with implanted 290-microns-diameter amperometric sensors. Boluses of 100, 200, and 400 mg/kg body wt were injected. The glucose concentration in the jugular vein was monitored by frequent withdrawal and analysis of samples. The glucose concentration in the subcutaneous tissue was continuously monitored with the sensors. The times required for the subcutaneously implanted sensor to reach its maximum current, corrected for sensor response times, were 7.5 +/- 3.9, 9.8 +/- 5.5, and 10.0 +/- 4.4 min for the smallest to the largest dose, respectively. The shorter delay in response to the smallest dose was statistically significant (P < 0.03). The results were consistent with dilution of the bolus in the cardiovascular system and transport of glucose by both diffusion and facilitated transport via a saturable mediator. An understanding of the differences in the dynamics of venous vs. subcutaneous response to a glucose dose is important in developing algorithms for the control of blood glucose based on a subcutaneous measurement.

From motilin to motilides: a new direction in gastrointestinal endocrinology

Investigation into gastrointestinal irritation from the use of erythromycin lead to the discovery of the gastrointestinal motor effect of this antibiotic. Erythromycin and gastrointestinal peptide motilin share many similar gastrokinetic activities, and studies indicate that erythromycin mimics the effect of motilin through motilin receptor agonism. Since erythromycin is readily available for clinical use, it may offer an alternative therapeutic approach to gastroparesis and related conditions. Several analogs of erythromycin without antimicrobial activity are also shown to possess similar motor effects, thus termed "motilides". A growing number of motilides may expand our knowledge on gastrointestinal peptides.

A comparison of fish oil or corn oil supplements in hyperlipidemic subjects with NIDDM

OBJECTIVE

To examine the effects on blood lipids and glycemic control of fish oil and corn oil supplementation at two levels in subjects with hyperlipidemia and non-insulin-dependent diabetes mellitus (NIDDM).

RESEARCH DESIGN AND METHODS

Forty subjects (18 men and 22 women; aged 53.9 +/- 7.0 years) with NIDDM and hyperlipidemia were randomly assigned to one of four treatment groups: 9 g of fish oil, 18 g of fish oil, 9 g of corn oil, or 18 g of corn oil daily supplementation for 12 weeks.

RESULTS

The level of oil supplements (9 g compared with 18 g) did not have a significant effect within each oil group on glycemic control and lipids. Significant differences (P < 0.05) in lipids were found when the 9-g and 18-g groups were combined. In subjects consuming fish oil, plasma very-low-density lipoprotein (VLDL) cholesterol (P = 0.0001), plasma triglyceride (TG) (P = 0.0001), and plasma VLDL TGs (P = 0.02 at 6 weeks and P = 0.0001 at 12 weeks) were significantly lowered compared with subjects consuming corn oil. Plasma VLDL cholesterol increased across time in the corn oil group (P = 0.04). Plasma low-density lipoprotein (LDL) cholesterol was temporarily increased (P = 0.008) in the fish oil group at 6 weeks, but the effect was no longer present at 12 weeks. No significant differences between fish oil- or corn oil-supplemented diets were found in total plasma cholesterol, high-density lipoprotein cholesterol, fasting plasma glucose, glycosylated HbA1c, weight, and blood pressure.

CONCLUSIONS

In this study, fish oil supplementation improved plasma VLDL cholesterol, VLDL TGs, and total TGs while having a transient deterioration in LDL cholesterol in subjects with NIDDM. Furthermore, fish oil supplementation had no significant deleterious effect on glycemic control.

Insulin withholding for weight control in women with diabetes

OBJECTIVE

To provide a description of the clinical characteristics that distinguish individuals who withhold insulin for weight control from those who do not. Some individuals with insulin-dependent diabetes mellitus (IDDM) control their weight by withholding insulin and purging excessive calories. This process places patients at risk for developing severe hyperglycemia, diabetic ketoacidosis, and increases the risk of long-term complications of diabetes.

RESEARCH DESIGN AND METHODS

Forty-two women with IDDM, ages 16-40, were interviewed and divided into two groups: insulin withholders (IWs) and non-insulin withholders (non-IWs). These groups were compared on physiological, behavioral, psychological, and psychiatric variables.

RESULTS

Compared with non-IWs, patients who withheld insulin to control their weight exhibited poorer glycemic control, reported more negative attitudes toward diabetes, were more likely to have pathological scores on the Eating Disorder Inventory 2, and were more likely to report current or past symptoms of anorexia or bulimia nervosa. IWs were also more likely to report lying to physicians about their degree of compliance with their diabetes regimens.

CONCLUSIONS

The results of this study indicated that IWs exhibit more symptoms associated with the spectrum of eating disorders than non-IWs. This study showed that insulin withholding for weight control not only exists, but is associated with some maladaptive symptoms and behaviors that need to be addressed by diabetes treatment teams.

Insulin requirements in lipodystrophic diabetes

A ten-fold increase in daily insulin requirements during the administration of total parenteral nutrition (TPN) is described in a patient with congenital generalized lipodystrophy, insulin-requiring diabetes mellitus, and acanthosis nigricans during an episode of acute pancreatitis secondary to hypertriglyceridaemia. After a period of 13 days on TPN, insulin requirements increased dramatically to an average of 1428 units per day for a period of 12 days, to achieve a mean blood glucose level of 10.9 mmol l-1. When the patient resumed feeding and the TPN was discontinued, the average daily insulin requirement was 104 units with a mean 24 h blood glucose of 11.8 mmol l-1. Parenteral administration of energy substrates in a rare case of diabetes mellitus and congenital lipodystrophy complicated by acute pancreatitis resulted in a severe insulin insensitive state due to the combination of the hypermetabolism conferred by the pancreatitis plus transient impairments of the glucose disposal mechanism by the energy substrates provided.

Genes for insulin-dependent diabetes mellitus (IDDM) in the major histocompatibility complex (MHC) of African-Americans

Mapping the MHC-associated susceptibility and resistance factors for insulin-dependent diabetes mellitus (IDDM) has been difficult due to the strong linkage disequilibrium within the HLA-DR-DQ region. Previous analyses have suggested that the study of IDDM-associated haplotypes in different races might be useful for identifying the responsible genes. We have performed complete HLA class II genotyping to study susceptibility and resistance to IDDM in 34 randomly selected African-American IDDM patients and 69 ethnically-matched controls. IDDM patients showed highly significant increases of DRB1*0301, DRB1*0401, DRB1*0405, DQA1*0301, DQA1*0302, DQB1*0201 and DQB1*0302. Analysis of DQA1-DQB1 associations showed that DQA1*03 combined with both DQB1*0201 and DQB1*0302 gave the highest odds ratio, suggesting a synergistic effect due to formation of heterodimers encoded both in cis and in trans. Among the subsets of DR4, only DRB1*0401 and DRB1*0405 were increased in diabetic patients. Interestingly, DQB1*0602 and DQB1*0301, which have previously been thought to encode resistance factors in Caucasians, were not significantly decreased and, after removal of known susceptibility haplotypes, were found to have essentially identical frequencies in patients and controls.

Association of erythrocyte aldose reductase activity with diabetic complications in type 1 diabetes mellitus

Erythrocyte aldose reductase was isolated and its activity measured in 72 Type 1 (insulin dependent) diabetic patients and 21 age and sex matched non-diabetic subjects. The diabetic patients were categorized into two groups in terms of presence (n = 29) or absence (n = 43) of severe diabetic complications. Age, sex, duration of diabetes and HbA1c levels were matched between the diabetic groups. Erythrocyte aldose reductase (mean +/- SEM) was increased in patients with Type 1 diabetes compared to the non-diabetic subjects (7.22 +/- 0.24 vs 5.66 +/- 0.19 Ul-erythrocytes-1, < 0.0001). There was a four-fold variation in its activity among the diabetic patients (3.38-12.23 Ul-erythrocytes-1). The enzyme activity was significantly higher in patients with complications than those without (8.17 +/- 0.39 vs 6.58 +/- 0.26 Ul-erythrocytes-1, p < 0.002). When the patients were stratified by duration of the disease, the enzyme activity was highest in patients who had developed complications with a duration of less than 20 years and lowest in those without complications for 20 years or longer (8.54 +/- 0.48 vs 6.46 +/- p +/- 0.33 Ul-erythrocytes-1, p < 0.002). Patients who had an aldose reductase activity greater than the mean +/- 2SD of that seen in non-diabetic controls were four times more likely to have diabetic complications than those whose enzyme activity fell within 2SD of non-diabetic individuals (p < 0.0005).(ABSTRACT TRUNCATED AT 250 WORDS)

Relationship between insulin sensitivity and degree of obesity in mild hypertension

Eighteen patients with mild hypertension (diastolic blood pressure > or = 90 and < 104 mm Hg) and 15 normotensive control subjects were studied. Insulin tolerance tests (ITT) and fasting plasma insulin (FPI) level measurements were performed to evaluate insulin sensitivity. Insulin sensitivity, as measured with the ITT, showed a strong correlation with body mass index (BMI) in the hypertensive and control groups (r = -0.68, p < 0.01 and r = -0.61, p < 0.01, respectively). The fasting insulin levels also correlated significantly with BMI in both groups (r = 0.55, p < 0.05 in the hypertensive and r = 0.76, p < 0.01 in the control group). Insulin sensitivity in the hypertensive subjects whose BMI was < or = 27.0 kg/m2 (nonobese), as measured with the ITT and FPI, was not different from the nonobese normal controls (K(itt), 5.36 +/- 1.74% min-1 versus 5.61 +/- 1.66% min-1, respectively, p > 0.2; FPI, 5.8 +/- 3.4 microU/ml versus 7.1 +/- 2.5 microU/ml, respectively, p > 0.2). Also, insulin sensitivity, as measured with the ITT, was not statistically significantly different between hypertensive and normotensive obese subjects (K(itt), 2.82 +/- 1.55% versus 3.90 +/- 0.67% min-1, respectively, p > 0.1). When fasting plasma insulin levels were compared, a higher level was observed in the obese normotensive subjects than in the obese hypertensive group (FPI, 19.8 +/- 10.0 microU/ml and 11.5 +/- 4.9 microU/ml, p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Correlation between erythrocyte aldose reductase activity and the width of skeletal-muscle capillary basement membrane in insulin-dependent diabetes mellitus

Thickening of capillary basement membrane has been demonstrated in diabetic subjects, and it is considered to be the characteristic pathological lesion of diabetic microvascular disease. There are studies reporting the effects of inhibitors of aldose reductase, the first enzyme of the polyol pathway, on the thickening of the capillary basement membrane. These observations indicate a significant role of the polyol pathway in the development of microvascular disease. However, it is unknown whether or not there is any correlation between the thickness of the capillary basement membrane and the activity of aldose reductase in diabetic patients. To clarify this issue, we measured the width of skeletal-muscle basement membrane and erythrocyte aldose reductase activity in 27 insulin-dependent diabetic and 8 nondiabetic individuals. The results showed that both the aldose reductase activity and the width of capillary basement membrane were increased in diabetic patients as compared to nondiabetic individuals (6.89 +/- 0.38 versus 5.15 +/- 0.60 mL/mU erythrocytes, p < 0.05 and 2257 +/- 166 versus 1136 +/- 69 A, p < 0.0001, respectively) (mean +/- SE), but marked variability was observed in both the enzyme activity and the basement membrane thickness among the diabetic patients. There was a significant correlation between the capillary basement membrane thickness and the activity of erythrocyte aldose reductase (r = 0.51, p < 0.01) in diabetic patients. Our data suggest that the polyol pathway plays an important role in thickening of capillary basement membrane in diabetic individuals, and the variability in aldose reductase activity seen among diabetic patients may result in the varying susceptibility to the development of diabetic microvascular disease.

Glycemic control and diabetic complications

The relationship between glycemic control and diabetic complications remains unclear. Epidemiological studies reveal that approximately 25% of diabetic individuals do not develop complications, irrespective of degree of glycemic control. Studies of genetic factors, including HLA type, capillary basement membrane thickness, genetic predisposition to hypertension, and familial clustering of diabetic complications, suggest that there is a genetic component to developing the complications of diabetes. On the other hand, clinical trials have demonstrated that the progression of early, mild background retinopathy, microalbuminuria, and parameters of nervous system function are stabilized with improved glycemic control. Other metabolic parameters, such as serum lipoprotein levels, are significantly improved with near normoglycemia. No studies to date have evaluated the effect of blood glucose control on the prevention of diabetic complications. The degree of glycemic control required to impact on diabetic complications is unknown. In addition, achieving near normoglycemia carries increased risk for severe hypoglycemia and weight gain. Further study is needed to determine the long-term benefits of blood glucose control and to weigh that against the risks of improving glycemic control. Further investigation also is needed to address the probable interrelationship of genetic factors and glycemic control on the development of diabetic complications.