Mechanism of action of sulphonylureas with special reference to the extrapancreatic effect: an overview

Sulfonylurea derivatives and cancer, friend or foe?

Type 2 diabetes mellitus (T2DM) is associated with a higher risk of cancer and cancer-related mortality. Increased blood glucose and insulin levels in T2DM patients may be, at least in part, responsible for this effect. Indeed, lowering glucose and/or insulin levels pharmacologically appears to reduce cancer risk and progression, as has been demonstrated for the biguanide metformin in observational studies. Studies investigating the influence of sulfonylurea derivatives (SUs) on cancer risk have provided conflicting results, partly due to comparisons with metformin. Furthermore, little attention has been paid to within-class differences in systemic and off-target effects of the SUs. The aim of this systematic review is to discuss the available preclinical and clinical evidence on how the different SUs influence cancer development and risk. Databases including PubMed, Cochrane, Database of Abstracts on Reviews and Effectiveness, and trial registries were systematically searched for available clinical and preclinical evidence on within-class differences of SUs and cancer risk. The overall preclinical and clinical evidence suggest that the influence of SUs on cancer risk in T2DM patients differs between the various SUs. Potential mechanisms include differing affinities for the sulfonylurea receptors and thus differential systemic insulin exposure and off-target anti-cancer effects mediated for example through potassium transporters and drug export pumps. Preclinical evidence supports potential anti-cancer effects of SUs, which are of interest for further studies and potentially repurposing of SUs. At this time, the evidence on differences in cancer risk between SUs is not strong enough to guide clinical decision making.

Potential Applications of Gliclazide in Treating Type 1 Diabetes Mellitus: Formulation with Bile Acids and Probiotics

A major advancement in therapy of type 1 diabetes mellitus (T1DM) is the discovery of new treatment which avoids and even replaces the absolute requirement for injected insulin. The need for multiple drug therapy of comorbidities associated with T1DM increases demand for developing novel therapeutic alternatives with new mechanisms of actions. Compared to other sulphonylurea drugs used in the treatment of type 2 diabetes mellitus, gliclazide exhibits a pleiotropic action outside pancreatic β cells, the so-called extrapancreatic effects, such as antiinflammatory and cellular protective effects, which might be beneficial in the treatment of T1DM. Results from in vivo experiments confirmed the positive effects of gliclazide in T1DM that are even more pronounced when combined with other hypoglycaemic agents such as probiotics and bile acids. Even though the exact mechanism of interaction at the molecular level is still unknown, there is a clear synergistic effect between gliclazide, bile acids and probiotics illustrated by the reduction of blood glucose levels and improvement of diabetic complications. Therefore, the manipulation of bile acid pool and intestinal microbiota composition in combination with old drug gliclazide could be a novel therapeutic approach for patients with T1DM.

Post-meal β-cell function predicts the efficacy of glycemic control in patients with type 2 diabetes inadequately controlled by metformin monotherapy after addition of glibenclamide or acarbose

BACKGROUND

This study aimed to explore parameters which will predict good control of HbA1c after adding a second anti-diabetic drug in patients with type 2 diabetes mellitus (T2DM) inadequately controlled with metformin monotherapy.

METHODS

Fifty-one patients (M/F: 25/26, mean age: 53.7 ± 8.2 years, mean glycated hemoglobin [HbA1c] 8.4 ± 1.2%) with T2DM inadequately controlled with metformin were randomized to add-on glibenclamide or acarbose for 16 weeks. Before and after combination therapy, the subjects underwent a 2-hour liquid mixed meal tolerance test to determine insulin secretion (HOMA-β, insulinogenic index, and disposition index [DI]) and insulin sensitivity (HOMA-IR and Matsuda insulin sensitivity index).

RESULTS

At baseline, there was a significant inverse relationship between DI120 and HbA1c (p = 0.001) in all subjects. The addition of glibenclamide and acarbose improved HbA1c significantly from 8.6 ± 1.6% to 7.4 ± 1.2% (p < 0.001), and from 8.2 ± 0.8% to 7.5 ± 0.8% (p < 0.001), respectively. In the glibenclamide group, DI120 significantly increased from 51.2 ± 24.2 to 74.9 ± 41.9 (p < 0.05), and in the acarbose group, from 62.5 ± 31.4 to 91.7 ± 36.2 (p < 0.05), respectively. Multiple regression analyses showed that both baseline HbA1c and DI120 independently predicted reduction of HbA1c as well as final HbA1c after combination therapy.

CONCLUSIONS

In patients with T2DM inadequately controlled with metformin, add-on oral anti-diabetic agent with glibenclamide or acarbose resulted in the significant HbA1c reduction and improvement of β-cell function. Subjects with greater baseline β-cell function reserve displayed better glycemic response in the combination therapy of metformin with glibenclamide or acarbose.

TRIAL REGISTRATION

This study was registered in the ClinicalTrials.gov with registration number of NCT00417729.

Antihyperglycemic effects of the methanol leaf extract of Diaphananthe bidens in normoglycemic and streptozotocin-induced hyperglycemic rats

OBJECTIVE

To evaluate the methanol leaf extract of Diaphanathe bidens (D. bidens) (AFZEL. EX SW) SCHLTR for antihyperglycemic activity in order to confirm it antidiabetic potential.

METHODS

D. bidens was extracted by cold maceration for 48 h and concentrated in vacuo to yield D. bidens extract (DBE). Hyperglycemia was induced by intraperitoneal administration of streptozotocin (75 mg/kg). Oral glucose tolerance test was done with 2 g/kg glucose load in normal rats. DBE (150, 300 and 600 mg/kg) was administered orally, while tolbutamide (100 mg/kg, p.o.) was used as the standard reference drug. Blood glucose levels determined using ACCUCHEK glucose auto-analyzer. The acute toxicity and phytochemical studies were also carried out.

RESULTS

DBE (600 mg/kg) and tolbutamide (100 mg/kg) significantly (P<0.05, 0.005) reduced blood glucose levels of rats between 120 and 480 min post administration in normal rats. In the streptozotocin- induced hyperglycemic rats, DBE (150, 300, 600 mg/kg) caused significant (P<0.001) dose- and time- dependent reduction in the blood glucose levels by 1.7%, 22.8% and 43.4%, respectively at 480 min compared to the negative control group. DBE (600 mg/kg) reduced the blood glucose level of rats by 1.2% in the oral glucose tolerance test when compared with the normal saline treated group. The acute toxicity test showed that DBE was safe at the doses used and the phytochemical screening revealed the presence of saponins, steroids, tannins and terpernoids.

CONCLUSIONS

D. bidens extract possess antihyperglycemic activity which may be mediated through pancreatic and extra-pancreatic pathways, thereby justifying it folkloric use.

Matrix type transdermal therapeutic systems of glibenclamide: Formulation, ex vivo and in vivo characterization

Matrix type transdermal therapeutic systems (TTS) of glibenclamide were formulated using polymers Eudragit RL 100, ethyl cellulose, PVP K-30, and polyvinyl acetate, and citral was used as the penetration enhancer. The polymer films were formulated with Eudragit RL 100 and PVP K-30 in different ratios and subsequently subjected to ex vivo studies (drug permeation through rat skin) followed by interaction studies, skin irritation studies, accelerated stability analysis, and in vivo studies (determination of blood glucose level in rabbits). The drug content of the formulations was found to be 99.1-99.2%. The cumulative percentages of drug permeated through rat skin from the three selected formulations in 48 h were 95.3%, 98.8%, and 99%, respectively. A plot between cumulative percent of drug permeated and square root of time exhibited linear curves, which suggests the Higuchian matrix mechanism of drug release. The formulation containing Eudragit RL 100 and PVP K-30 showed better improvement in hypoglycemic activity in rabbits (56.2-60.8% reduction in blood glucose level, p < 0.05). There were fewer fluctuations in blood glucose level as compared to oral therapy due to controlled release of the active pharmaceutical ingredient, and no interaction was found between the drug and excipients of the formulation. Accelerated stability analysis showed that the formulation was stable up to 5.5 years, with negligible skin irritation. The formulation precluded severe hypoglycemic reactions (side effect of sulfonylureas) and was effective for management of diabetes mellitus up to 48 h, with a single TTS.

Sulfonylureas and the risk of myocardial infarction

Patients with diabetes mellitus have an increased risk of coronary artery diseases such as myocardial infarction. Sulfonylureas are used in the treatment of diabetes mellitus and have been linked with adverse cardiovascular effects due to an apparent effect on myocardial ischemic preconditioning. Individual sulfonylureas differ pharmacologically and may have different effects. Although the hypotheses were stimulated by animal studies and experimental studies using intermediate end points, data on the possible clinical implications in humans remain sparse. However, recent data seem reassuring.

Myocardial glucose utilisation in type II diabetes mellitus patients treated with sulphonylurea drugs

PURPOSE

Chronic sulphonylurea treatment maintains improved glycaemic control through mechanisms other than enhancement of insulin secretion and may act on various organs. The aim of this study was to investigate whether the chronic use of sulphonylurea drugs influences PET measurement of myocardial glucose utilisation (MGU) in type II diabetes mellitus.

METHODS

Forty-two patients with type II diabetes mellitus and 17 control subjects underwent dynamic (18)F-FDG PET to measure MGU during hyperinsulinaemic euglycaemic clamping. Twenty-one patients had been taking sulphonylurea drugs for more than 1 year (SU group), and the other 21 patients were drug naive (non-SU group). The haemoglobin A1c levels in the two patient groups were similar. Glucose disposal rate (GDR) was also determined as a marker of whole-body insulin resistance.

RESULTS

GDR in the SU group (9.01+/-2.53 mg min(-1) kg(-1)) was significantly higher than that in the non-SU group (4.10+/-2.47, p<0.01) and was similar to that in the controls (9.76+/-2.97). MGU in the SU group (7.66+/-3.02 mg min(-1) 100 g(-1)) was significantly higher than that in the non-SU group (5.53+/-2.05, p<0.01) and was similar to that in the controls (7.49+/-2.74).

CONCLUSION

Chronic sulphonylurea treatment influences MGU independent of the degree of glycaemic control. The effect of medication should be kept in mind when measuring and interpreting MGU in patients with type II diabetes mellitus.

Glimepiride improves both first and second phases of insulin secretion in type 2 diabetes

OBJECTIVE

The purpose of this study was to assess the effect of glimepiride on insulin sensitivity and secretion in subjects with type 2 diabetes.

RESEARCH DESIGN AND METHODS

After a 2-week washout from prior sulfonylurea therapy, 11 obese subjects with type 2 diabetes underwent euglycemic and hyperglycemic clamp studies before and during glimepiride therapy.

RESULTS

Glimepiride resulted in a 2.4-mmol/l decrease in fasting plasma glucose (P = 0.04) that was correlated with reductions in postabsorptive endogenous glucose production (EGP) (16.4 +/- 0.6 vs. 13.5 +/- 0.5 micro mol. kg(-1). min(-1), P = 0.01) (r = 0.21, P = 0.01). Postabsorptive EGP on glimepiride was similar to that of control subjects (12.8 +/- 0.9 micro mol. kg(-1). min(-1), NS). Fasting plasma insulin (66 +/- 18 vs. 84 +/- 48 pmol/l, P = 0.05), and first-phase (19 +/- 8 vs. 32 +/- 11 pmol/l, P = 0.04) and second-phase incremental insulin responses to glucose (48 +/- 23 vs. 72 +/- 32 pmol/l, P = 0.02) improved with glimepiride therapy. Insulin sensitivity did not change with treatment (4.6 +/- 0.7 vs. 4.3 +/- 0.7 micro mol. kg(-1). min(-1). pmol(-1)) and remained below that of control subjects (8.1 +/- 1.8 micro mol. kg(-1). min(-1). pmol(-1), P = 0.04).

CONCLUSIONS

The current study demonstrates that glimepiride improves both first and second phases of insulin secretion, but not insulin sensitivity, in individuals with type 2 diabetes.

Effects of dietary treatment alone or diet with voglibose or glyburide on abdominal adipose tissue and metabolic abnormalities in patients with newly diagnosed type 2 diabetes

OBJECTIVE; To examine the effects of diet and diet with voglibose or glyburide on abdominal adiposity and metabolic abnormalities in patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

A total of 36 Japanese patients with newly diagnosed type 2 diabetes (50.8 +/- 8.6 years of age, BMI 24.5 +/- 3.5 kg/m(2)) and 273 normal control subjects were studied. The patients were treated for 3 months with diet alone (30 kcal/kg per day) (n = 15), diet with voglibose (n = 12), or diet with glyburide (n = 9). They underwent 75-g oral glucose tolerance testing, assessment of insulin sensitivity (SI), and acute insulin response (AIR) with intravenous glucose tolerance testing based on the minimal model, and measurement of abdominal visceral adipose tissue area (VAT) and subcutaneous adipose tissue area (SAT) by computed tomography before and after treatment.

RESULTS

The diabetic patients had comparable SAT but larger VAT than the control subjects. With a mean weight loss of 2-3 kg, VAT and SAT were decreased similarly in all treatment groups. The VAT-to-SAT ratio was decreased only in the voglibose group. Glycemic control and serum lipid profiles were improved in all groups. Changes in glycemic control after diet were closely correlated with changes in VAT but not with changes in SAT. SI and AIR were unchanged in the diet group but were improved in the voglibose and glyburide groups.

CONCLUSIONS

In Japanese patients with newly diagnosed type 2 diabetes who were relatively lean but had excess VAT, diet with or without voglibose or glyburide effectively reduced VAT. Decrease in VAT was closely associated with improvement of glycemic control with diet. Additional use of voglibose or low-dose glyburide had no detrimental effects on abdominal adiposity and had beneficial effects on SI and AIR.

Established therapies for diabetes mellitus

Traditional oral anti-diabetic agents for the treatment of diabetes mellitus include the sulfonylureas, metformin, and the alpha-glucosidase inhibitors. Insulin has traditionally been used in various forms with an aim to mimic physiological insulin secretion patterns. Combinations of any of these treatment classes have also been utilized for their additive effects. All of these options have specific advantages and disadvantages, making them ideal for certain patients and less ideal for others. Each of these treatment classes is briefly discussed with respect to mechanisms of action, clinical efficacy, side-effects and current controversies associated with their use. Newer agents (such as the thiazolidinediones, newer insulin secretagogues, and insulin analogues) will be discussed elsewhere.

Pioglitazone hydrochloride in combination with sulfonylurea therapy improves glycemic control in patients with type 2 diabetes mellitus: a randomized, placebo-controlled study

PURPOSE

To evaluate the efficacy and tolerability of pioglitazone in combination with a sulfonylurea in the treatment of type 2 diabetes mellitus.

SUBJECTS AND METHODS

This 16-week, double-blind study included patients on a stable regimen of a sulfonylurea for > or = 30 days and with a glycosylated hemoglobin (HbA1C) level > or = 8.0%. Patients were randomly assigned to receive once daily pioglitazone 15 mg (n = 184), pioglitazone 30 mg (n = 189), or placebo plus sulfonylurea (n = 187).

RESULTS

Patients receiving pioglitazone + sulfonylurea had significant (P < 0.05) decreases from baseline in HbA1C and fasting plasma glucose levels compared with patients treated with placebo + sulfonylurea. As compared with placebo, HbA1C decreased by 0.9% (95% confidence interval [CI]: 0.06% to 1.2%) with pioglitazone 15 mg and 1.3% (CI: 1% to 1.6%) with 30 mg pioglitazone; fasting plasma glucose levels decreased by 39 mg/dL (95% CI: 27 to 52 mg/dL) with pioglitazone 15 mg and by 58 mg/dL (95% CI: 46-70 mg/dL) with 30 mg pioglitazone. Both pioglitazone + sulfonylurea groups had significant (P < 0.05) mean percent decreases in triglyceride levels (17%, 95% CI: 6% to 27% for 15 mg; 26%, 95% CI: 16% to 36% for 30 mg) and increases in high-density lipoprotein cholesterol levels (6%, 95% CI: 1% to 11% for 15 mg; 13%, CI: 8% to 18% for 30 mg) compared with placebo + sulfonylurea. There were small but statistically significant mean percent increases in low-density lipoprotein cholesterol levels in all groups. Pioglitazone was well tolerated, and the rates of adverse events were similar in all groups.

CONCLUSION

In patients with type 2 diabetes, pioglitazone plus sulfonylurea significantly improves HbA1C and fasting plasma glucose levels with beneficial effects on serum triglyceride and HDL-cholesterol levels.

Non insulin-dependent diabetes mellitus (type 2) secondary failure. Metformin-glibenclamide treatment

The goal of sulphonylurea (S) treatment in Non-Insulin-Dependent Diabetes Mellitus (NIDDM - type 2 diabetes) subjects should be to obtain a satisfactory glycemic control (fasting glycemic levels &#x003C; 140 mg&#x0025;). The loss of an adequate blood glucose control after an initial variable period of S is known as secondary failure (SF). The number of SF are extremely variable among different trials for many reasons, some of which are patient-related: increased food intake, weight gain, non-compliance, poor physical activity, stress, diseases and&#x00F7;or impaired pancreatic beta cell function, desensitization after S chronic therapy, reduced absorption, concomitant therapies. Many therapeutic strategies have been proposed to achieve an adequate metabolic control in type 2 diabetes patients: switch to intensive insulin therapy and subsequent return to S therapy; association with insulin; association with sulphonylureas plus biguanides. The association biguanides and S, in particular glibenclamide plus metformin, is now widely used by diabetologists in SF since glibenclamide improves insulin secretion while metformin exerts its antidiabetic.

Pharmacotherapy of type 2 diabetes mellitus

OBJECTIVE

To review the drug treatments and some of the popular, nontraditional remedies now available for type 2 diabetes mellitus, as well as selected investigational agents; to describe each medication's place in the overall approach to treatment.

DATA SOURCES

English-language journals, abstracts, review articles, and newspaper accounts.

DATA SYNTHESIS

In the past five years, there has been tremendous progress in the pharmacotherapy of diabetes, particularly type 2 diabetes. Several new agents have entered the clinical arena, and many more are in the late stages of investigation leading to approval. Sulfonylureas stimulate the production and release of insulin; these drugs must be used in patients with an intact pancreas. The meglitinides are nonsulfonylurea agents that are also insulin secretagogues. Unlike the sulfonylureas, repaglinide appears to require the presence of glucose to close the adenosine triphosphate-sensitive potassium channels and induce calcium influx. Metformin reduces hepatic glucose production in some patients and increases peripheral glucose utilization, but its use is hampered by a high percentage of adverse reactions. Disaccharidase inhibitors effectively compensate for the defective early-phase insulin release by slowing the production of sugars from carbohydrates. Thiazolidinediones appear to activate peroxisome proliferator-activated receptor gamma, which is involved in the metabolism of lipids. Short-acting insulin and the role of weight-loss agents are also discussed.

CONCLUSIONS

The availability of new options for diabetes therapy provides a chance for successful therapy in a larger number of patients. However, it is important to consider how much true benefit these new forms of treatment will have on the diabetic community. The best choice for a patient remains controversial.

Sulfonylurea effects on acid and pepsinogen secretion in isolated rabbit gastric glands

The influence of different sulfonylureas on the rate of acid and pepsinogen secretion was studied in isolated rabbit gastric glands. Neither tolbutamide (10-500 microM), chlorpropamide (10-500 microM), glibenclamide (1-50 microM) nor glipizide (1-50 microM) exerted a secretory effect. In contrast, gliquidone caused a marked and dose-dependent stimulation of acid production in gastric glands incubated under basal conditions and potentiated the stimulatory effect of both histamine and carbachol. Gliquidone also increased the rate of pepsinogen release in gastric glands incubated either under basal conditions or in the presence of cholecystokinin-octapeptide or isoproterenol. The secretory effects of gliquidone were associated with a significant increase in the glandular content of cyclic AMP, caused by a competitive inhibition of low-Km cyclic AMP phosphodiesterase. Our results indicate that, among the assayed sulfonylureas, only gliquidone, in the micromolar range, stimulates acid and pepsinogen secretion through a cyclic AMP-dependent mechanism.

Efficacy of combination therapy in non-insulin dependent diabetes mellitus

Secondary failure of oral hypoglycaemic agents raises the dilemma of whether to institute therapy with insulin alone, or in combination. We reviewed our experience of combination therapy following secondary failure of oral hypoglycaemic therapy. Seventeen subjects were receiving combination therapy for 6 months or more. Such treatment was associated with a significant fall in HbA1C--from 10.7 +/- 0.38 per cent to 8.3 +/- 0.35 per cent (p < 0.01) after 6 months and remained significantly reduced at 12 months (8.7 +/- 0.34 per cent (p < 0.01)). Mean body weight, systolic and diastolic blood pressure were unchanged during treatment with adjuvant insulin therapy. Insulin therapy is a useful adjunct in the daily management of subjects with NIDDM who experience secondary failure of oral hypoglycaemic agents.

Drug treatment of non-insulin-dependent diabetes mellitus in the 1990s. Achievements and future developments

Non-insulin-dependent diabetes mellitus (NIDDM, type 2 diabetes) is a heterogeneous disease resulting from a dynamic interaction between defects in insulin secretion and insulin action. There are various pharmacological approaches to improving glucose homeostasis, but those currently used in clinical practice either do not succeed in restoring normoglycaemia in most patients or fail after a variable period of time. For glycaemic regulation, 4 classes of drugs are currently available: sulphonylureas, biguanides (metformin), alpha-glucosidase inhibitors (acarbose) and insulin, each of which has a different mode and site of action. These standard pharmacological treatments may be used individually for certain types of patients, or may be combined in a stepwise fashion to provide more ideal glycaemic control for most patients. Adjunct treatments comprise a few pharmacological approaches which may help to improve glycaemic control by correcting some abnormalities frequently associated with NIDDM, such as obesity (serotoninergic anorectic agents) and hyperlipidaemia (benfluorex). There is intensive pharmaceutical research to find new drugs able to stimulate insulin secretion (new sulphonylurea or nonsulphonylurea derivatives, glucagon-like peptide-1), improve insulin action (thiazolidinediones, lipid interfering agents, glucagon antagonists, vanadium compounds) or reduce carbohydrate absorption (miglitol, amylin analogues, glucagon-like peptide-1). Further studies should demonstrate the superiority of these new compounds over the standard antidiabetic agents as well as their optimal mode of administration, alone or in combination with currently available drugs.

Non-insulin-dependent diabetes mellitus in childhood and adolescence

NIDDM in children and adolescents represents a heterogeneous group of disorders with different underlying pathophysiologic mechanisms. Most subtypes of NIDDM that occur in childhood are uncommon, but some, such as early onset of "classic" NIDDM, seem to be increasing in prevalence. This observed increase is thought to be caused by societal factors that lead to sedentary lifestyles and an increased prevalence of obesity. In adults, hyperglycemia frequently exists for years before a diagnosis of NIDDM is made and treatment is begun. Microvascular complications, such as retinopathy, are often already present at the time of diagnosis. Children are frequently asymptomatic at the time of diagnosis, so screening for this disorder in high-risk populations is important. Screening should be considered for children of high-risk ethnic populations with a strong family history of NIDDM with obesity or signs of hyperinsulinism, such as acanthosis nigricans. Even for children in these high-risk groups who do not yet manifest hyperglycemia, primary care providers can have an important role in encouraging lifestyle modifications that might delay or prevent onset of NIDDM.

Hypoglycaemic and insulinotropic effects of a novel oral antidiabetic agent, (-)-N-(trans-4-isopropylcyclohexanecarbonyl)-D-phenylalanine (A-4166)

1. (-)-N-(trans-4-isopropylcyclohexanecarbonyl)-D-phenylalanine (A-4166), a novel oral hypoglycaemic agent is a non-sulphonylurea insulin secretagogue. 2. We investigated the insulin-releasing action and hypoglycaemic effect of A-4166 compared to sulphonylureas in vitro and in vivo. 3. A-4166 stimulated insulin secretion from rat freshly isolated pancreatic islets at concentrations from 3 x 10(-6) M to 3 x 10(-4) M in the presence of 2.8 mM glucose. There was no obvious difference in glucose dependency between the insulinotropic effect of A-4166 and that of glibenclamide, and no additive or synergistic effect was observed between these two drugs. 4. A-4166 displaced [3H]-glibenclamide bound to intact HIT-T15 cells in a concentration-dependent manner. The Ki value was 4.34 +/- 0.04 x 10(7) M, and the displacement potency of A-4166 was between that of glibenclamide and tolbutamide, being similar to that of gliclazide. 5. Inf fasted beagle dogs, A-4166 showed a dose-dependent hypoglycaemic effect after oral administration over the range 1 to 10 mg kg-1. The hypoglycaemic action of A-4166 showed an earlier onset and a shorter duration than that of sulphonylureas. 6. Simultaneous measurement of plasma insulin levels revealed that the hypoglycaemic effect of A-4166 was caused by a rapid-onset and brief burst of insulin secretion. 7. The pharmacokinetic profile of A-4166 was consistent with the changes of the blood glucose and plasma insulin levels. 8. Although the in vitro insulin-releasing effect of A-4166 was similar to that of sulphonylureas, its hypoglycaemic effect was more rapid and shorter-lasting, associated with rapid absorption and clearance. Thus, A-4166 may be useful in suppressing postprandial hyperglycaemia in patients with non-insulin-dependent diabetes mellitus.

Glyburide increases the secretion, tissue uptake, and action of insulin in conscious normal dogs

The action of glyburide on glucose homeostasis involves pancreatic and extrapancreatic mechanisms. The relative importance of each of these processes in the hypoglycemic response to sustained administration of glyburide is unknown. In addition, the effect of this drug on the hepatic extraction of insulin is controversial. This investigation uses direct techniques in conscious normal dogs to examine the impact of glyburide therapy (2.5 mg twice daily for 4 weeks) on glucose homeostasis. Preparatory surgery included placement of Doppler flow probes on hepatic vessels and insertion of catheters in carotid artery, portal vein, hepatic vein, and renal vein. After recovery from surgery, animals underwent an intravenous glucose tolerance test ([IGTT] 0.3 g - kg (-1) intravenous glucose bolus) and an insulin infusion clamp test ([IICT] 2 mU - kg (-1) - min (-1) intravenous insulin during 150 minutes) followed by glyburide therapy. After 4 weeks, the IGTT and IICT were repeated. Glyburide increased the insulin secretory response during the late phase of the IGTT and augmented glucose clearance during the IICT. Hepatic extraction of insulin was also stimulated by glyburide. We conclude that the hypoglycemic action of long-term glyburide administration involves stimulation of both insulin secretion by the pancreas and glucose disposal by peripheral tissues. In addition, glyburide augments the extraction of insulin by the liver, and such an effect might prevent the development of sustained high levels of insulin in blood perusing peripheral tissues.

Antidiabetic plants and their active constituents

Diabetes mellitus is a debilitating and often life-threatening disease with increasing incidence in rural populations throughout the world. A scientific investigation of traditional herbal remedies for diabetes may provide valuable leads for the development of alternative drugs and therapeutic strategies. Alternatives are clearly needed because of the inability of current therapies to control all of the pathological aspects of diabetes, and the high cost and poor availability of current therapies for many rural populations, particularly in developing countries. This review provides information on more than 1200 species of plants reported to have been used to treat diabetes and/or investigated for antidiabetic activity, with a detailed review of representative plants and some of great diversity of plant constituents with hypoglycemic activity, their mechanisms of action, methods for the bioassay of hypoglycemic agents, potential toxicity problems, and promising directions for future research on antidiabetic plants. The objective of this work is to provide a starting point for programs leading to the development of indigenous botanical resources as inexpensive sources for standardized crude or purified antidiabetic drugs, and for the discovery of lead compounds for novel hypoglycemic drug development.

Unchanged gene expression of glycogen synthase in muscle from patients with NIDDM following sulphonylurea-induced improvement of glycaemic control

We have previously shown that the mRNA expression of muscle glycogen synthase is decreased in non-insulin-dependent diabetic (NIDDM) patients; the objective of the present protocol was to examine whether the gene expression of muscle glycogen synthase in NIDDM is affected by chronic sulphonylurea treatment. Ten obese patients with NIDDM were studied before and after 8 weeks of treatment with a weight-maintaining diet in combination with the sulphonylurea gliclazide. Gliclazide treatment was associated with significant reductions in HbA1C (p=0.001) and fasting plasma glucose (p=0.005) as well as enhanced beta-cell responses to an oral glucose load. During euglycaemic, hyperinsulinaemic clamp (2 mU x kg-1 x min-1) in combination with indirect calorimetry, a 35% (p=0.005) increase in whole-body insulin-stimulated glucose disposal rate, predominantly due to an increased non-oxidative glucose metabolism (p=0.02) was demonstrated in teh gliclazide-treated patients when compared to pre-treatment values. In biopsies obtained from vastus lateralis muscle during insulin infusion, the half-maximal activation of glycogen synthase was achieved at a significantly lower concentration of the allosteric activator glucose 6-phosphate (p=0.01). However, despite significant increases in both insulin-stimulated non-oxidative glucose metabolism and muscle glycogen synthase activation in gliclazide-treated patients no changes were found in levels of glycogen synthase mRNA or immunoreactive protein in muscle. In conclusion, improved blood glucose control in gliclazide-treated obese NIDDM patients has no impact on the gene expression of muscle glycogen synthase.

Glipizide stimulates sympathetic outflow in diabetes-prone mice

The purpose of the present study was to determine if the oral hypoglycemic agent glipizide influenced sympathetic outflow in diabetes-prone mice. C57BL/6 (diabetes-prone) and diabetes-resistant (A/J) were treated with saline or glipizide, and sympathetic outflow determined by the fall in organ norepinephrine content after synthesis inhibition with alpha-methyl-para-tyrosine. Sympathetic outflow to the liver and pancreas were slower in Bl/6 mice than in control A/J. Glipizide increased sympathetic outflow to the pancreas in both strains of mice, but did not influence outflow to other organs significantly. The results of this study suggest that glipizide can influence central glucoregulatory mechanisms after peripheral administration.

Effects of glipizide on glucose metabolism and muscle content of the insulin-regulatable glucose transporter (GLUT 4) and glycogen synthase activity during hyperglycaemia in type 2 diabetic patients

To examine whether sulphonylureas influence hyperglycaemia-induced glucose disposal and suppression of hepatic glucose production (HGP) in type 2 diabetes mellitus, a 150-min hyperglycaemic (plasma glucose 14 mmol/l) clamp with concomitant somatostatin infusion was used in eight type 2 diabetic patients before and after 6 weeks of glipizide (GZ) therapy. During the clamp a small replacement dose of insulin was given (0.15 mU/kg per min). Isotopically determined glucose-induced glucose uptake was similar before and after GZ administration which led to improved glycaemic control (basal plasma glucose 12.2 +/- 1.3 vs 8.9 +/- 0.7 mmol/l; P < 0.01). Glucose-induced suppression of HGP was, however, more pronounced during GZ treatment (0.96 +/- 0.14 vs 1.44 +/- 0.20 mg/kg per min; P < 0.02). Following GZ treatment hyperglycaemia failed to stimulate glycogen synthase activity. Moreover, GZ resulted in a significant increase in the immunoreactive abundance of the insulin-regulatable glucose transport protein (GLUT 4) (P < 0.02). In conclusion, these results suggest that GZ therapy in type 2 diabetic patients enhances hepatic sensitivity to hyperglycaemia, while glucose-induced glucose uptake remains unaffected. In addition, GZ tends to normalize the activity of glycogen synthase and increases the content of GLUT 4 protein in skeletal muscle.

Mechanism(s) of the blood glucose lowering action of benfluorex

Benfluorex is a hypolipidaemic agent with biguanide-like properties. To evaluate its blood glucose lowering action, a single-blind study protocol was designed. Two groups of seven type II (non-insulin-dependent) diabetic patients matched for age (50 +/- 4 vs. 53 +/- 1 years), sex, body mass index (27.8 +/- 0.6 vs. 26.5 +/- 0.7 kg/m2), and duration of diabetes were studied before and after 1 month of treatment with benfluorex 150 mg tid (= tres in die = three times a day), PO (= per os = by mouth) or a placebo, respectively. All patients had previously been treated by diet alone. In all patients, parameters of glucose and lipid metabolism were obtained. Insulin sensitivity was assessed by means of a euglycaemic (5.1 +/- 0.1 mM) hyperinsulinaemic (516 +/- 28 pM) clamp performed in combination with [3(-3)H]glucose infusion and indirect calorimetry. In no case was there a significant change in body mass index (27.6 +/- 0.5 vs. 26.4 +/- 0.7 kg/m2). After 1 month of treatment, fasting plasma glucose (6.8 +/- 0.2 vs. 8.1 +/- 0.6 mM) and HbA1C (glycated haemoglobin; 6.5 +/- 0.2 vs. 8.0 +/- 0.7%) were lower in the benfluorex group than in the placebo-treated patients (both p < 0.05). No change was observed in hepatic glucose production (HGP) (13.5 +/- 1.4 vs. 13.9 +/- 1.1 mumol/min per kg), the basal rate of glucose, and lipid oxidation and non-oxidative glucose metabolism, or in plasma triglyceride and total cholesterol concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of a new oral hypoglycaemic agent, repaglinide, on metabolic control in sulphonylurea-treated patients with NIDDM

We have evaluated the effects of repaglinide, a new non-sulphonylurea oral hypoglycaemic agent that has a stimulatory effect on insulin secretion. Forty-four patients with NIDDM, already treated with a sulphonylurea, took part in an open, randomised, group comparison study of 12 weeks duration, during which they received either repaglinide or glibenclamide twice daily. While glibenclamide had a greater effect on fasting blood glucose (10.4 to 8.6 mmol.l-1), repaglinide significantly lowered postprandial blood glucose (13.8 to 12.2 mmol.l-1). Glycosylated haemoglobin remained unchanged in both groups, and serum fructosamine showed a tendency to fall. With both treatments total cholesterol was significantly decreased after 12 weeks, while HDL-cholesterol and triglycerides did not change. Fasting plasma insulin in the repaglinide group decreased from 80 (median value) to 67 pmol.l-1; it did not change in the glibenclamide group. Two patients in the repaglinide group did not complete the study, one for personal reasons, and one because of a rise in blood glucose. No abnormal findings attributable to repaglinide were observed in clinical and laboratory examinations, and no hypoglycaemic symptoms caused by it were observed.

Effect of value-added utilities on prescription refill compliance and Medicaid health care expenditures--a study of patients with non-insulin-dependent diabetes mellitus

An estimated 20 million Americans suffer from diabetes. Patients with non-insulin-dependent diabetes mellitus (NIDDM) comprise approximately 90% of the diabetic population. An estimated 10-30% of patients with NIDDM withdraw from their prescribed regimen within 1 year of diagnosis, and of the remainder, nearly 20% administer insufficient medication to facilitate an adequate reduction in blood glucose. A randomized trial was undertaken to discern the effect of pharmacy-based value-added utilities on prescription-refill compliance with sulfonylurea therapy and health service utilization. The subjects were 258 Medicaid beneficiaries from the state of South Carolina, previously untreated for NIDDM, prescribed 5 mg of the second-generation sulfonylurea glyburide twice daily, and monitored with regard to prescription-refill compliance and health service utilization for 1 year. Subjects provided informed consent and were randomly assigned to one of four experimental groups: (i) the control cohort received standard pharmaceutical care with each dispensing of glyburide; (ii) the second cohort received standard pharmaceutical care and was mailed a medication-refill reminder 10 days prior to each sequential refill date; (iii) the third cohort received standard pharmaceutical care and was provided unit-of-use packaging with each prescription-refill request; (iv) the fourth cohort received standard pharmaceutical care, mailed medication-refill reminders, and unit-of-use packaging. Analysis of variance (ANOVA) procedures revealed that patients receiving mailed prescription-refill reminders, unit-of-use packaging, or a combination of both interventions achieved a significant (P < or = 0.05) increase in the Medication Possession Ratio (MPR) for sulfonylurea therapy relative to controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Serious, prolonged hypoglycaemia with glibenclamide in a patient with Mendenhall's syndrome

Mendenhall's syndrome, characterized by familial insulin resistant diabetes, pineal hyperplasia and multiple somatic abnormalities, is associated with defects involving the alpha-subunit of the insulin receptor. The associated insulin-resistant diabetes is extremely difficult to treat; insulin is required in very large doses to control hyperglycaemia and oral hypoglycaemic agents are ineffective. We report a case of severe, prolonged hypoglycaemia that occurred in a 24-year-old patient with Mendenhall's syndrome following therapy with glibenclamide. He had glibenclamide 10 mg daily for 1 week following which he was admitted to hospital in hypoglycaemic coma with blood glucose levels < 1.0 mmol/l. This subject had undergone hypophysectomy at the age of 11 years. Prior to pituitary ablation, oral hypoglycaemic agents did not improve glycaemic control. Thus, previous hypophysectomy in this patient appears to have made it possible for glibenclamide to exert its hypoglycaemic effect. The occurrence of hypoglycaemia in this patient suggests alternative mechanisms for insulin action in conditions characterized by severe insulin resistance due to insulin receptor defects.

Does glibenclamide influence the clearance of insulin and glucose uptake in patients with type 2 diabetes mellitus?

Sulphonylureas have been proposed to decrease the clearance of insulin based on the finding that they increase peripheral insulin concentrations more than C-peptide concentrations. However, direct evidence for such an effect has so far been lacking. The aim of this study was to investigate whether glibenclamide affects clearance of insulin in Type 2 diabetic patients. Nine patients with Type-2 diabetes participated in the study. Insulin clearance and glucose metabolism was assessed with a 240 min euglycaemic insulin clamp in combination with infusion of somatostatin (400 micrograms h-1) to completely suppress endogenous insulin secretion. Either saline or glibenclamide was infused throughout the clamp in random order. During both the glibenclamide and the saline protocol the C-peptide level declined to < 0.07 nmol l-1 within 150 min, indicating that insulin secretion was completely suppressed. However, peripheral clamp insulin concentrations remained similar during both saline and glibenclamide protocols (3374 +/- 258 vs. 3350 +/- 265 pmol l-1 x 240 min, p = NS). There was no significant difference in the metabolic clearance rate of insulin during the glibenclamide compared to the saline experiment neither during the first 120 min (796 +/- 36 vs. 757 +/- 34 ml m-2min-1) nor during the last 2 h of the clamp (780 +/- 43 vs. 724 +/- 35 ml m-2min-1). Total glucose metabolism during the first two (14 +/- 2 vs. 15 +/- 2 mumol kg-1 min-1) and the last 2 h of the clamp was similar both during saline and glibenclamide infusions (27 +/- 4 vs. 28 +/- 4 mumol kg-1min-1).(ABSTRACT TRUNCATED AT 250 WORDS)

Sulfonylureas activate glycogen phosphorylase and increase cytosolic free-Ca2+ levels in isolated rat hepatocytes

Without causing significant changes in cellular levels of cyclic adenosine monophosphate (cAMP), the addition of either glibenclamide or gliquidone to isolated rat hepatocytes caused a transient dose- and Ca(2+)-dependent activation of glycogen phosphorylase. The calculated concentrations corresponding to half-maximal activation were 5 and 2 mumol/L, respectively. In connection with this, it was observed that glibenclamide provoked a dose-dependent increase in cytosolic free-calcium concentration ([Ca2+]i) in Fura-2-loaded hepatocytes. Moreover, the presence of glibenclamide in the incubation medium accelerated the rate of Ca2+ uptake by Ca(2+)-depleted hepatocytes. These findings suggest that an increase in [Ca2+]i could mediate some of the effects of sulfonylureas in liver metabolism.

The inhibitory action of buformin, a biguanide on gluconeogenesis from alanine and its transport system in rat livers

The effect of buformin, a biguanide, on gluconeogenesis from 10 mM alanine in the presence of 143 nM glucagon were studied using isolated rat liver perfusions. In addition, to investigate possible mechanisms of biguanide action, alanine utilization in isolated rat liver perfusion and [3H]alanine uptake in isolated hepatocytes were observed. Buformin (1.85 mM) strongly inhibited gluconeogenesis from alanine in the presence of glucagon in both normal and streptozocin-induced diabetic rat livers. This inhibition was followed by a decrease in alanine utilization. Both of these inhibitory effects of buformin were dose-dependent. [3H]Alanine uptake was significantly inhibited by buformin. The effect of this agent was similar to but weaker than that of ouabain. However, tolbutamide failed to reduce either alanine utilization or [3H]alanine uptake, although this drug significantly inhibited gluconeogenesis from alanine. These data suggest that biguanides may reduce hepatic alanine utilization via the inhibition of Na+/L-alanine transport activity as one possible mechanism, resulting the inhibition of gluconeogenesis from alanine in the presence of glucagon.

Effects of the combination of insulin and gliclazide compared with insulin alone in type 2 diabetic patients with secondary failure to oral hypoglycemic agents

Twenty non-insulin-dependent diabetic patients on insulin therapy for more than 2 months due to secondary failure to oral hypoglycemic agents (OHA) were additionally treated with gliclazide, 80 mg b.i.d., for 1 month and 160 mg b.i.d. for a further 2 months, while reducing insulin dose gradually according to glycemic control. At the end of the first month, fasting blood glucose had decreased from 12.8 +/- 0.7 to 9 +/- 0.8 mM (mean +/- standard error; P < 0.005) and thereafter remained stable. Insulin requirements decreased from 34.2 +/- 2.5 to 18.3 +/- 3.2 U/day (P < 0.001). Three patients were able to cease insulin treatment altogether. A direct correlation was found between final insulin dose and previous duration of infusion monotherapy (r = 0.52; P < 0.05). C-peptide/glucose score (fasting C-peptide/fasting BG x 100) increased from 0.11 +/- 0.03 to 0.21 +/- 0.05 (P < 0.05). We conclude that combined therapy reduces insulin requirement by increasing endogenous secretion, which may mainly affect hepatic glucose production as indicated by greater improvement in fasting vs. post-prandial blood glucose. This therapy could avoid hyperinsulinemia, which has been reported to be involved in macrovascular complications, and the additional haemovascular properties of gliclazide could make it more effective in such a combination.

Hepatic sensitivity to insulin: effects of sulfonylurea drugs

Insulin regulation of hepatic glucose production (HGP) is altered in non-insulin-dependent diabetes mellitus (NIDDM), resulting in increased glucose output by the liver; this contributes to the elevation in plasma glucose concentration observed both in the basal state and postprandially. Therefore, restoration of normal insulin action in the liver must be a goal of hypoglycemic therapy. Sulfonylureas have been widely used for treatment of NIDDM over the past 30 years. In addition to their stimulatory effect on insulin secretion, these compounds seem to possess extrapancreatic effects. Early in vitro studies showed that addition of sulfonylureas to the perfusion medium of liver preparations could exert a significant suppressive effect on HGP. Subsequent experience suggested that these compounds could act at the level of the insulin receptor as well as at various postreceptor sites. These studies showed that sulfonylureas may inhibit glycogenolysis and gluconeogenesis while stimulating glycogen synthesis. Results obtained in vivo in NIDDM patients are in agreement with the in vitro studies. Long-term treatment with sulfonylureas is associated with a decline in fasting plasma glucose concentration and a parallel reduction in HGP. Nevertheless, the direct effect of sulfonylurea administration on the liver remains unclear, since the reduction in HGP that occurs during sulfonylurea treatment may be secondary to an overall improvement in insulin secretion. It is also of interest that in insulin-dependent diabetic patients, sulfonylurea administration in combination with insulin injections is not followed by a significant change in HGP. Possible effects of sulfonylureas on glucagon secretion and on the metabolism of free fatty acids (FFAs) may also contribute to improved sensitivity of the liver to the suppressive action of insulin, since these agents appear to reduce plasma glucagon and FFA concentrations. Thus, present data support an extrapancreatic action of sulfonylureas on the liver. However, it does appear that a certain degree of residual insulin secretion is required for sulfonylurea agents to elicit their hepatic effect.

Effects of sulfonylureas on adipocyte and skeletal muscle insulin action in patients with non-insulin-dependent diabetes mellitus

The effect of glibenclamide treatment on insulin action in isolated fat cells was studied in eight moderately obese patients with non-insulin-dependent diabetes mellitus (NIDDM). Insulin receptor binding and the effect of insulin on glucose transport and lipogenesis were determined before and after 3 months of glibenclamide therapy. At the end of the treatment period, mean daytime plasma glucose concentrations were reduced (10.8 +/- 0.4 versus 7.0 +/- 0.3 mmol/L, p less than 0.001) whereas mean daytime plasma insulin level was increased (40 +/- 12 versus 71 +/- 9 mU/L, p less than 0.001). Adipocyte insulin receptor binding as well as basal glucose transport and metabolism were unaffected by drug treatment. In contrast, insulin-stimulated glucose transport and lipogenesis were both significantly enhanced (p less than 0.05). These findings are comparable to those of another study involving seven moderately obese subjects with NIDDM who had biopsies of the lateral vastus muscle taken for measurement of insulin receptor function and glycogen synthase activity before and during 2 months of gliclazide treatment. In that study insulin receptors purified with wheatgerm agglutinin showed unchanged insulin binding and receptor kinase activity. Moreover, gliclazide had no impact on maximal glycogen synthase activity. However, under physiologic hyperinsulinemic conditions gliclazide therapy was associated with an increased sensitivity of glycogen synthase for its allosteric activation by glucose-6-phosphatase (p less than 0.04). In conclusion, sulfonylurea treatment of NIDDM enhances insulin-stimulated peripheral glucose utilization in part through a potentiation of insulin action on adipose tissue glucose transport and lipogenesis and skeletal muscle glycogen synthase.

The mode of action and clinical pharmacology of gliclazide: a review

Gliclazide is a sulphonylurea drug with an intermediate half-life of around 11 hours. It is extensively metabolised, and renal clearance accounts for only 4% of total drug clearance. The molecule contains an azabicyclo-octyl group which confers special properties on the basic sulphonylurea moiety. Gliclazide stimulates insulin secretion through the beta cell sulphonylurea receptor, and possibly through a direct effect on intracellular calcium transport. It specifically improves the abnormal first phase insulin release in type 2 diabetes, and also has an effect on the second phase. This pattern of insulin release is thought to explain the lower incidence of hypoglycaemic episodes and weight gain compared with some other sulphonylureas. There is also a reduction in hepatic glucose production and improvement in glucose clearance, without changes in insulin receptors. This suggests a possible post-receptor effect on insulin action, perhaps by stimulation of hepatic fructose-2,6-bisphosphatase and muscle glycogen synthase. Gliclazide reduces platelet adhesion, aggregation and hyperactivity and increases fibrinolysis. These actions, thought to be independent of its hypoglycaemic activity, may make gliclazide useful in halting the progression of diabetic microangiopathy.

History and evolution of the concept of oral therapy in diabetes

The object of diabetes treatment is to restore adequate carbohydrate, protein and lipid metabolism. The cornerstone of this treatment has been diet since the end of the 18th century, but true antidiabetic therapy started only with the identification and purification of insulin. Pressure for oral therapy then quickly built up. The hypoglycemic effect of guanidines was discovered in 1919, leading to their therapeutic use, but they were withdrawn in 1932 due to their hepatotoxic effects. The related biguanides appeared in the 1950s but have since diminished in importance so that metformin is practically the only representative still used today. Work in the 1940s and 1950s led to the discovery and development of hypoglycemic sulfonylureas (SU), a therapeutic class unique for its specificity and safety. These products were found to stimulate insulin secretion by the endocrine pancreas. In vitro studies have shown that they bind specifically to an ATP-dependent K+ channel of the beta cell membrane. This binding closes the channel so that K+ outflow ceases, the beta cell membrane depolarizes and voltage-dependent Ca2+ channels open to allow an influx of extracellular calcium. The result is migration and extrusion of insulin granules. Although this mechanism of action has been demonstrated in vitro, it cannot account for all the clinical actions of various SU. They thus appear to have extrapancreatic actions, probably potentiating the peripheral effects of insulin at a postreceptor site in target cells. Other effects involve fibrinolytic activity of the blood, platelet behavior and vascular reactivity. The future of oral diabetes therapy thus seems to lie with the sulfonylureas.

Combination of insulin with glipizide increases peripheral glucose disposal in secondary failure type 2 diabetic patients

Twenty Type 2 diabetic patients, recently converted to insulin because of inadequate control on oral hypoglycaemic agents, were studied. Endogenous insulin reserve was measured by glucagon stimulation, and insulin-mediated peripheral glucose disposal by a hyperglycaemic (11 mmol l-1) clamp, measurements being repeated after 8 weeks of glipizide or placebo therapy in addition to the patients' usual insulin. The study was randomized and double blind. Fasting and stimulated C-peptide levels did not change on glipizide or placebo. Insulin-mediated glucose disposal rose from 2.5 (1.5-8.0) (median (range] to 4.2 (2.3-8.4) mg kg-1 min-1 in the glipizide group (n = 9, p less than 0.01), but did not change in the placebo group. Glycosylated haemoglobin did not change in either group, but median fasting plasma glucose fell from 10.6 (6.1-15.1) to 9.0 (6.4-11.2) mmol l-1 in the glipizide group (p less than 0.02). Fasting insulin rose on glipizide from 10.1 (4.0-23.2) to 13.0 (6.4-33.8) mU l-1 (p less than 0.02). Insulin dosage fell in the glipizide group from 36 to 26 U day-1, as 4 patients experienced hypoglycaemic symptoms. HDL-Cholesterol fell in all patients on glipizide, from 0.94 (0.79-2.13) to 0.79 (0.62-1.95) mmol l-1 (p less than 0.01). Combination of insulin with the sulphonylurea glipizide in secondary failure Type 2 diabetic patients leads to increased insulin-mediated peripheral glucose disposal. Glipizide may have an adverse effect on HDL-cholesterol, which is unrelated to change in diabetic control.