Rosiglitazone treatment of patients with extreme insulin resistance and diabetes mellitus due to insulin receptor mutations has no effects on glucose and lipid metabolism

SGLT2i Improves Glycemic Control in Patients With Congenital Severe Insulin Resistance

Insulin-resistant diabetes in Rabson-Mendenhall syndrome (RMS) is relatively unresponsive to first-line antidiabetic treatments, including metformin and insulin. We report 2 patients with RMS treated with 2 different sodium-glucose cotransporter inhibitors 2: empagliflozin in an 11-year-old boy and dapagliflozin in a 12-year-old girl. In the first patient, we began empagliflozin at 2.5 mg/day and increased the dose to 10 mg/day over 3 months. During treatment with empagliflozin, the amount of time during which the patient maintained serum glucose in the 70 to 180 mg/dL target range increased by 2 hours per day. Hemoglobin A1C dropped from >14% to 11.9%, urinary calcium increased almost twofold, and β-hydroxybutyrate remained <2.5 mmol/L. Because glycemic control did not further improve with dose escalation, we reverted to the 2.5 mg/day dose. We initiated dapagliflozin in a second patient at 5 mg/day and witnessed a reduction of hemoglobin A1C from 8.5% to 6.2% after 6 months and a mild increase in urinary excretion of phosphorus but not calcium. Insulin levels fell by >50%. In 2 patients with RMS, empagliflozin and dapagliflozin were well tolerated and improved glycemic control without significantly increasing ketonemia. Renal calcium excretion should be carefully monitored.

Identification of a novel mutation in patients with type A insulin resistance syndrome

INTRODUCTION

Type A insulin resistance syndrome is a rare type of congenital insulin resistance often caused by heterozygous mutations in the insulin receptor gene (INSR). The aim of this study is to explore the clinical and genetic characteristics of three patients with type A insulin resistance syndrome from two Chinese families.

METHODS

The peripheral blood samples were collected from each family members. Whole-exome sequencing were performed on three patients.

RESULTS

Patient #1 was diagnosed with hyperinsulinemia at the age of 11 years and presented with hirsutism, acanthosis nigricans, and polycystic ovaries by 13 years. A heterozygous c.3470A > G mutation in the INSR gene was identified in patient #1. Patient #2 was a 13-year-old girl who presented with insulin resistance, polycystic ovary, and hyperandrogenemia. A novel c.3601C > G INSR mutation was identified in patient #2. Co-segregated analysis showed that the c.3601C > G mutation was also found in her father, who had hyperinsulinemia and diabetes mellitus, which was consistent with autosomal dominant inheritance. SIFT and PolyPhen-2 predicted that the c.3470A > G and c.3601C > G mutations in INSR had damaging effects.

CONCLUSION

Our study expands the genotypic and phenotypic spectrum of type A insulin resistance syndrome. Awareness of the clinical features coupled with INSR gene screening is key to early detection and active intervention.

Glimepiride treatment in a patient with type A insulin resistance syndrome due to a novel heterozygous missense mutation in the insulin receptor gene

AIMS/INTRODUCTION

Glimepiride is a sulfonylurea known to have unique insulin mimetic and sensitizing effects. We aimed to study the efficacy of glimepiride in a patient with type A insulin resistance syndrome.

MATERIALS AND METHODS

A 15-year-old girl with type A insulin resistance syndrome was treated with glimpiride for 6 months. Self-monitoring of blood glucose was recorded, and oral glucose tolerance tests on glucose and insulin were measured during the treatment. Hyperinsulinemic euglycemic clamp was used to evaluate whole-body insulin sensitivity before and after the treatment.

RESULTS

A novel heterozygous missense mutation at exon 19 (c.3427A>T) in the tyrosine kinase domain of the INSR gene was identified, causing an amino acid replacement of phenylalanine for isoleucine at codon 1143 (Ile1143Phe). Before the treatment, the patient's glycated hemoglobin was 7.0%, plasma glucose during oral glucose tolerance test was 6.7, 12.8 and 17.3 mmol/L, and simultaneous serum insulin was 80.7, 137.5 and >300 μU/mL. There were no significant differences between self-monitored blood glucose measured at each time-point among different glimepiride dosages, or during the 14 weeks when glimepiride was used at its maximal dosage (6 mg/day). Oral glucose tolerance test showed little change in plasma glucose and serum insulin. Glycated hemoglobin decreased by 0.8% after the treatment. However, a euglycemic clamp study showed that the M value decreased from 5.25 to 2.90 mg/kg/min, showing increased insulin resistance.

CONCLUSIONS

Treatment with glimepiride did not improve insulin sensitivity in a patient with type A insulin resistance syndrome carrying Ile1143Phe heterozygous mutation in the INSR gene. Large-scale long-term studies assembled worldwide are required to optimize treatment algorithms for patients with type A insulin resistance syndrome.

Diagnostic and management challenges from childhood, puberty through to transition in severe insulin resistance due to insulin receptor mutations

Two Caucasian girls, both of normal weight and body mass indices, were diagnosed with type A insulin resistance (IR) in childhood. Case 1 presented with premature adrenarche aged 7 years, then by age 12 years had hirsutism, acne, acanthosis nigricans, and asymptomatic diabetes. Subsequent investigation revealed raised adiponectin (15.3 mg/L) and heterozygous p.Pro1205Leu mutation in the INSR gene encoding the insulin receptor. She experienced postprandial hypoglycaemia on metformin; acarbose was trialled and discontinued aged 16 years, as she became normoglycaemic. Hirsutism was treated with topical eflornithine, oral spironolactone and flutamide, and laser therapy. Unfortunately, diabetes reemerged in young adulthood with obesity. Case 2: during an emergency admission for acute abdominal pain aged 11 years, hyperglycaemia was noted which led to further investigation. An oral glucose tolerance test showed diabetes and ultrasound showed polycystic ovaries. Further investigations revealed raised adiponectin (18 mg/L) and compound heterozygous mutations in the INSR gene: p.Pro1263Ala and p.Ser748Leu (latter probable normal variant). She was treated with metformin and experienced postprandial hypoglycaemia. Symptoms of hyperandrogenism were controlled by flutamide. She maintained a healthy weight and reassessment at young adulthood showed resolution of diabetes. Type A IR may present in childhood with overlapping features of common endocrine entities such as premature adrenarche and polycystic ovarian syndrome. Patients with abnormal glucose tolerance yet normal weight merit screening with adiponectin; raised adiponectin levels prompt insulin receptor mutational analysis. Postprandial hypoglycaemia is characteristic. Management includes optimization of glycaemic control with oral hypoglycaemic agents and maintenance of healthy weight, and controlling the effects of hyperandrogenism.

Novel mutation in insulin receptor gene identified after muscle biopsy in a Niuean woman with severe insulin resistance

BACKGROUND

Severe, early-onset insulin resistance in the absence of obesity, hepatic steatosis and dyslipidaemia is frequently attributable to a genetic defect affecting the insulin receptor. We describe a patient with severe insulin resistance in whom insulin receptor mutation analysis was mistakenly recorded as normal. Western blot analysis of skeletal muscle showed reduced insulin receptor protein and led to re-evaluation of the insulin receptor and the discovery of a novel mutation.

CASE REPORT

A Niuean women, first evaluated at age 6 years for severe acanthosis nigricans, hirsutism, poor growth and cognitive impairment, had extremely elevated fasting insulin levels of 10740 IU/l (fasting reference range 4-24 IU/l) and a normal glucose concentration (4.9 mmol/l). Diabetes was diagnosed at age 9 years and metformin treatment introduced. By age 14 years, she developed refractory hyperglycaemia despite metformin, rosiglitazone and 240 IU insulin daily. Insulin receptor genetic analysis was documented as normal. At age 23 years, with a blood glucose concentration of 37 mmol/l and an HbA1c concentration of 116 mmol/mol, U500 insulin 2000 IU/day was required for glycaemic control. She developed severe proliferative diabetic retinopathy with neovascular glaucoma leading to blindness. There was no renal dysfunction, dyslipidaemia or hepatic steatosis. A muscle biopsy was performed to evaluate the insulin signalling pathway and showed reduced insulin receptor protein. Sequencing of the insulin receptor showed a homozygous p.Val1010Leu missense mutation.

CONCLUSION

This patient illustrates the use of muscle biopsy in the evaluation of a patient with unexplained severe insulin resistance. This approach may usefully be applied to other cases of severe insulin resistance, where genetic testing for known mutations in the insulin signalling pathway has been negative.

Genetic Variation and Insulin Resistance in Middle-Aged Chinese Men

We investigated the effect of variants in the first three genes in the insulin signaling pathway and genes identified from genome wide association studies (GWAS) of T2D quantitative traits with IR (fasting insulin and the homeostasis model assessment of IR, HOMA-IR) and evaluated gene-environment interactions with IR traits among 1879 nondiabetic middle-aged men from a population-based study conducted in Shanghai, China. One candidate gene, IGF1, was associated with fasting insulin and HOMA-IR. We observed four BMI-gene interactions (P < 0.05) with HOMA-IR (INRS rs7254060, INRS rs7254358, GLU4 rs2113050, and GLU4 rs7713127) and seven BMI-gene interactions with fasting insulin (INRS rs7254060, INRS rs7254358, INRS rs10417205, INRS rs1799817, GLU4 rs12054720 GLU4 rs2113050, and GLU4 rs7713127). There were four WHR-gene interactions with HOMA-IR (INRS rs10417205, INRS rs12971499, INRS rs7254060, and INRS rs7254358), five WHR-gene interactions with fasting insulin (INRS rs10417205, INRS rs7254060, INRS rs7254358, GLU4 rs2113050, and GLU4 rs7713127), eight physical activity-gene interactions with HOMA-IR (INRS rs10411676, INRS rs11671297, INRS rs2229431, INRS rs12461909, INRS rs6510950, INRS rs10420382, IRS2 rs913949, and IRS2 rs2241745) and five physical activity-gene interactions with fasting insulin (INRS rs2229431, INRS rs12461909, INRS rs10420382, IRS2 rs913949, and IRS2 rs2241745). Our results suggest that BMI, WHR and physical activity may modify IR-associated variants.

Insulin receptor variants and obesity-related cancers in the Framingham Heart Study

PURPOSE

The insulin-signaling pathway plays a pivotal role in cancer biology; however, evidence of genetic alterations in human studies is limited. This case-control study nested within the Framingham Heart Study (FHS) examined the association between inherited genetic variation in the insulin receptor (INSR) gene and obesity-related cancer risk.

METHODS

The study sample consisted of 1,475 controls and 396 cases from the second familial generation of the FHS. Participants who provided consent were genotyped. Nineteen single-nucleotide polymorphisms (SNPs) in the INSR gene were investigated in relation to risk of obesity-related cancers combined and breast, prostate and colorectal cancers. Generalized estimation equation models controlling for familial correlations and include age, sex, smoking and body mass index as covariates, assuming additive models, were used.

RESULTS

Three SNPs, rs2059807, s8109559 and rs919275, were significantly associated with obesity-related cancers (p value < 0.02) with the most significantly associated SNP being rs2059807 (p value = 0.008). Carriers of two copies of SNP rs2059807 risk allele T were significantly less prevalent among subjects with obesity-related cancers [f(TT)cases = 14 vs. f(TT)controls = 18 %; OR 1.23]. In exploratory analyses evaluating site-specific cancers, the INSR rs2059807 association with these cancers was consistent with that observed for the main outcome (ORs colorectal cancer = 1.5, breast cancer = 1.29, prostate = 1.06). There was no statistically significant interaction between the INSR-SNP and blood glucose in relation to obesity-related cancer.

CONCLUSIONS

The INSR gene is implicated in obesity-related cancer risk, as 3 of 19 SNPs were nominally associated, after false discovery rate (FDR) correction, with the main outcome. Risk allele homozygotes (rs2059807) were less prevalent among subjects with obesity-related cancer. These results should be replicated in other populations to confirm the findings.

An observational study of the effect of two thiazolidinediones on blood lipid levels: Rosiglitazone and pioglitazone in routine clinical practice

BACKGROUND

Rosiglitazone maleate and pioglitazone hydrochloride are established antihyperglycemic agents that are effective when used as monotherapy or in combination with other medications. However, the data regarding the effects of these agents on blood lipid levels are contradictory.

OBJECTIVE

The aim of this study was to determine whether the use of rosiglitazone and pioglitazone in clinical practice is associated with any changes in blood lipid levels.

METHODS

A retrospective chart review using electronic medical record data was conducted of patients with type 2 diabetes mellitus who were newly treated with either rosiglitazone or pioglitazone and had 1 lipid measurement within 6 months prior to and 12 months following initial thiazolidinedione (TZD) therapy. Outcome measures were mean changes in low- and high-density lipoprotein cholesterol (LDL-C and HDL-C, respectively). To control for differences in baseline characteristics and/or selection bias, the treatment cohorts were compared using multivariate statistical techniques.

RESULTS

A total of 371 patients were included in the study; the pioglitazone cohort comprised 148 patients (82 women, 66 men; mean [SD] age, 64.9 [10.8] years) and the rosiglitazone cohort comprised 223 patients (113 men, 110 women; mean [SD] age, 66.1 [11.9] years). Pioglitazone-treated patients had a statistically higher mean baseline LDL-C compared with rosiglitazone-treated patients (125.0 mg/dL vs 116.6 mg/dL; P = 0.04). On average, LDL-C levels decreased over the study period, with no significant differences between the 2 cohorts (9.9 mg/dL vs 4.3 mg/dL for pioglitazone and rosiglitazone, respectively), although changes in both cohorts were statistically significant (P < 0.001).

CONCLUSIONS

TZD therapy appears to be associated with a small decrease in LDL-C within the first 6 months after initiation. No differences in changes in LDL-C or HDL-C could be discerned between patients treated with rosiglitazone compared with pioglitazone.

Differential sensitivities of the vascular K(ATP) channel to various PPAR activators

Several agonists of the peroxisome proliferator-activated receptors (PPARs) are currently used for the treatment of metabolic disorders including diabetes. We have recently shown that one of them, Rosiglitazone, inhibits the vascular ATP-sensitive K⁺ (K(ATP)) channel and compromises the coronary vasodilation by the β-adrenoceptor agonist. Here, we show evidence for the channel inhibition by various PPAR agonists, information that may be useful for finding new therapeutical agents with less cardiovascular side-effects and more selective K(ATP) channel blockers targeting at the K(ir)6.1 subunit. Structural comparison of these PPAR agonists may shed insight into the critical chemical groups for the channel inhibition. K(ir)6.1/SUR2B channel was expressed in HEK293 cells and studied in whole-cell voltage clamp. The K(ir)6.1/SUR2B channel was strongly inhibited by several PPAR(γ) agonists with potencies similar to, or higher than, that of Rosiglitazone, while other PPAR(γ) agonists barely inhibited the channel. The K(ir)6.1/SUR2B channel was also inhibited by PPAR(α) and PPAR(β/δ) agonists with intermediate potencies. The structure necessary for the channel inhibition appears to include the thiazole linked to an aromatic or furan ring. Additions of side groups such as small aliphatic chain increased the potency for channel inhibition, while additions of aromatic rings reduced it. These results indicate that the PPAR(γ) agonists with weak K(ATP) channel inhibition may be potential candidates as therapeutical agents, and those with strong channel inhibition may be used as selective K(ATP) channel blockers. The structural information of the PPAR agonists may be useful for the development of new therapeutical modalities with less cardiovascular side-effects.

What is the best management strategy for patients with severe insulin resistance?

Management of severe insulin resistance (IR) is a major clinical challenge in many patients with obesity or lipodystrophy, and also in rarer patients with proven or suspected genetic defects in the insulin receptor or downstream signalling. The latter group can present at any time between birth and early adult life, with a variable clinical course broadly correlated with the severity of IR. Primary insulin signalling defects are usually associated with poor weight gain rather than obesity. Initially, extreme hyperinsulinaemia produces ovarian enlargement and hyperandrogenism in women, and often fasting or postprandial hypoglycaemia. However, any hypoglycaemia gradually evolves into insulin-resistant hyperglycaemia when beta cell function declines. Optimal management of these complex disorders depends on early diagnosis and appropriate targeting of both high and low glucose levels. In newborns, continuous nasogastric feeding may reduce harmful glycaemic fluctuations, and in older patients, acarbose may mitigate postprandial hypoglycaemia. Insulin sensitization, initially with metformin but later with trials of additional agents such as thiazolidinediones, is the mainstay of early therapy, but insulin replacement, eventually with very high doses, is required once diabetes has supervened. Preliminary data suggest that rhIGF-1 can improve survival in infants with the most severe insulin receptor defects and also improve beta cell function in older patients with milder receptoropathies. The utility of newer therapies such as glucagon-like peptide-1 agonists and dipeptidyl peptidase-IV inhibitors remains untested in this condition. Thus, management of these patients remains largely empirical, and there is a pressing need to collate data centrally to optimize treatment algorithms.

Insulin resistance-related genes and advanced left-sided colorectal adenoma

BACKGROUND

Insulin resistance has been linked with colorectal neoplasia through a number of mechanistic and observational studies. Allelic variants of genes encoding components of the insulin pathway, including insulin (INS), insulin receptor (INSR), and insulin receptor substrate-1 and insulin receptor substrate-2 (IRS1 and IRS2) have been associated with hyperinsulinemia and insulin resistance and may, therefore, predict susceptibility to colorectal neoplasia.

METHODS

We investigated whether single nucleotide polymorphisms (SNP) in the INS, INSR, IRS1, and IRS2 genes are associated with risk of advanced left-sided colorectal adenoma, a cancer precursor. We analyzed 20 SNPs in a largely Caucasian study population comprising 766 cases with advanced adenomas of the distal colon and 771 controls, all of whom had undergone flexible sigmoidoscopy as part of the screening arm of the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial.

RESULTS

Overall, we found limited evidence for a role of gene variants of the insulin signaling pathway and prevalence of advanced colorectal adenoma. We observed a statistically significant interaction between INSR genotypes and body mass index (BMI) with colorectal adenoma prevalence (P value for global test = 0.003) and suggestion of an interaction between INSR genotypes and glycemic load (P value for global test = 0.06); however, exploration of the interaction of BMI and glycemic load with the individual SNPs in INSR did not suggest a single SNP that may explain the significance of these global tests of interaction and did not yield any consistent patterns.

CONCLUSION

These findings do not provide strong evidence for associations between polymorphic variation in genes of the insulin signaling pathway and advanced left-sided colorectal adenoma. Evidence for interaction between INSR variants and BMI and glycemic load for risk of advanced left-sided colorectal adenoma requires independent confirmation, and genotyping of INSR across a broader region and at greater density may be necessary to fully elucidate the nature of these interactions.

Oral insulin-mimetic compounds that act independently of insulin

The hallmarks of insulin action are the stimulation and suppression of anabolic and catabolic responses, respectively. These responses are orchestrated by the insulin pathway and are initiated by the binding of insulin to the insulin receptor, which leads to activation of the receptor's intrinsic tyrosine kinase. Severe defects in the insulin pathway, such as in types A and B and advanced type 1 and 2 diabetes lead to severe insulin resistance, resulting in a partial or complete absence of response to exogenous insulin and other known classes of antidiabetes therapies. We have characterized a novel class of arylalkylamine vanadium salts that exert potent insulin-mimetic effects downstream of the insulin receptor in adipocytes. These compounds trigger insulin signaling, which is characterized by rapid activation of insulin receptor substrate-1, Akt, and glycogen synthase kinase-3 independent of insulin receptor phosphorylation. Administration of these compounds to animal models of diabetes lowered glycemia and normalized the plasma lipid profile. Arylalkylamine vanadium compounds also showed antidiabetic effects in severely diabetic rats with undetectable circulating insulin. These results demonstrate the feasibility of insulin-like regulation in the complete absence of insulin and downstream of the insulin receptor. This represents a novel therapeutic approach for diabetic patients with severe insulin resistance.

Molecular mechanisms of insulin resistance and associated diseases

Insulin resistance is a state in which higher than normal concentrations of insulin are required for normal response. The most common underlying cause is central obesity, although primary insulin resistance in normal-weight individuals is also possible. Excess abdominal adipose tissue has been shown to release increased amounts of free fatty acids which directly affect insulin signalling, diminish glucose uptake in muscle, drive exaggerated triglyceride synthesis and induce gluconeogenesis in the liver. Other factors presumed to play the role in insulin resistance are tumour necrosis factor alpha, adiponectin, leptin, IL-6 and some other adipokines. Hyperinsulinaemia which accompanies insulin resistance may be implicated in the development of many pathological states, such as hypertension and hyperandrogenaemia. Insulin resistance underlies metabolic syndrome and is further associated with polycystic ovary syndrome and lipodystrophies. When beta-cells fail to secrete the excess insulin needed, diabetes mellitus type 2 emerges, which is, besides coronary heart disease, the main complication of insulin resistance and associated diseases.

Metformin (Glucophage) inhibits tyrosine phosphatase activity to stimulate the insulin receptor tyrosine kinase

Metformin is a commonly used anti-diabetic but whether its mechanism involves action on the insulin receptor or on downstream events is still controversial. With a time course that was slow compared with insulin action, metformin increased tyrosine phosphorylation of the regulatory domain of the insulin receptor (specifically, tyrosine residues 1150 and 1151). In a direct action, therapeutic levels of metformin stimulated the tyrosine kinase activity of the soluble intracellular portion of the beta subunit of the human insulin receptor toward a substrate derived from the insulin receptor regulatory domain. However, metformin did not alter the order of substrate phosphorylation by the insulin receptor kinase. Using a Xenopus oocyte preparation, we simultaneously recorded tyrosine kinase and phosphatase activities that regulate the insulin receptor by measuring the tyrosine phosphorylation and dephosphorylation of peptides derived from the regulatory domain of the human insulin receptor. In an indirect stimulation of the insulin receptor, metformin inhibited endogenous tyrosine phosphatases and purified human protein tyrosine phosphatase 1B that dephosphorylate and inhibit the insulin receptor kinase. Thus, there was evidence that metformin acted directly upon the insulin receptor and indirectly through inhibition of tyrosine phosphatases.

Effects of insulin-sensitising agents in mice with hepatic insulin resistance

AIMS/HYPOTHESIS

The metabolic abnormalities of insulin resistance are ameliorated by insulin sensitisers via different mechanisms. Metformin decreases hepatic glucose output, whereas rosiglitazone (RSG) is an agonist for peroxisome proliferator activated receptor (PPAR)gamma, highly expressed in fat. To gain insight into the mechanisms of action of these drugs, we compared their actions in two models of insulin resistance: the obese, hyperglycaemic ob/ob mouse and the liver specific insulin receptor knockout (LIRKO) mouse.

METHODS

Control, ob/ob, and LIRKO mice were divided into three groups that received metformin (300 mg/kg body weight/day), RSG (3 mg/kg body weight/day), or placebo for 3 weeks.

RESULTS

In the presence of the severe hepatic insulin resistance of the LIRKO mouse, neither metformin nor RSG had any significant effect on glucose or insulin tolerance tests. On the other hand, RSG decreased serum concentrations of total cholesterol, LDL, and HDL in LIRKO mice. Adipocyte PPARgamma gene and protein expression, and adipocyte size were all increased in LIRKO mice treated with RSG, whereas fat-cell size in control animals was decreased by RSG.

CONCLUSION/INTERPRETATION

TZDs probably improve some lipid parameters of the dysmetabolic syndrome associated with diabetes mellitus even in the presence of absolute hepatic insulin resistance, but both metformin and TZDs require an operating insulin signalling system in the liver for their effects in glucose homeostasis.

Rosiglitazone improves insulin sensitivity and lowers blood pressure in hypertensive patients

OBJECTIVE

To examine the effect of rosiglitazone on insulin resistance and blood pressure in patients with essential hypertension, classified based on abnormalities of their renin-angiotensin system.

RESEARCH DESIGN AND METHODS

A total of 24 hypertensive nondiabetic patients (age 58 +/- 6 years, BMI 30 +/- 5 kg/m2) were studied before and after rosiglitazone treatment. After 2 weeks off antihypertensive medication, subjects received a euglycemic-hyperinsulinemic clamp (40 mU. m(-2). min(-1)) with 6,6-[2H2]glucose infusion, ambulatory blood pressure monitoring, and blood tests for cardiovascular risk factors. Subjects were then placed on rosiglitazone (4 mg orally b.i.d.) and their usual antihypertensive medications (but not ACE inhibitors) for 16 weeks, and baseline tests were repeated.

RESULTS

There was no change in fasting plasma glucose (83 +/- 2 vs. 82 +/- 2 mg/dl, P = 0.60), but fasting insulin decreased (16.1 +/- 1.4 vs. 12.5 +/- 0.9 micro U/ml, P < 0.01). Total glucose disposal during the clamp increased (5.0 +/- 0.4 vs. 5.9 +/- 0.5 mg. kg(-1). min(-1), P < 0.001), with no change in suppression of hepatic glucose output. There were significant decreases in mean 24-h systolic (138 +/- 2 vs. 134 +/- 2 mmHg, P < 0.02) and diastolic (85 +/- 2 vs. 80 +/- 2 mmHg, P < 0.0001) blood pressure, and the decline in systolic blood pressure was correlated with the improvement in insulin sensitivity (r = 0.59, P < 0.005). Triglycerides (135 +/- 16 vs. 89 +/- 8 mg/dl, P < 0.01), LDL cholesterol (129 +/- 6 vs. 122 +/- 8 mg/dl, P = 0.18), and HDL cholesterol (51 +/- 3 vs. 46 +/- 3 mg/dl, P < 0.02) all decreased, with no change in the LDL-to-HDL ratio. Plasminogen activator inhibitor-1 and C-reactive protein also declined significantly.

CONCLUSIONS

Rosiglitazone treatment of nondiabetic hypertensive patients improves insulin sensitivity, reduces systolic and diastolic blood pressure, and induces favorable changes in markers of cardiovascular risk. Insulin sensitizers may provide cardiovascular benefits when used in the treatment of patients with hypertension.

Insulin therapy for reducing cardiovascular risk in patients with type 2 diabetes

Twenty-four percent of the adult American population have the metabolic syndrome. Although somewhat counterintuitive, carefully regulated treatment with insulin has been shown to reduce insulin resistance and may also retard the development of cardiovascular disease by preventing chronic hyperglycemia, a condition that synergistically contributes to many proatherogenic pathways, including glycoxidation, the polyol pathway, advanced glycation end products, interference with normal metabolic pathways, and stimulation of protein kinase C-beta and proinflammatory pathways. This article describes some of the physiologic changes that occur when hyperglycemia and insulin resistance develop in patients with type 2 diabetes and discusses therapies, including insulin, that normalize glucose and reduce insulin resistance, thereby potentially reducing cardiovascular risk.