Comparison of pharmacokinetics, metabolic effects and mechanisms of action of glyburide and glipizide during long-term treatment

Development and in vitro characterization of humanized antibodies for blocking human TRPM4 channel

Transient receptor potential melastatin 4 (TRPM4) channel, a monovalent cation channel, plays a crucial role in various neurological disorders. We previously showed that TRPM4 activity can be blocked by our antibodies: M4P, which targets rat TRPM4 and M4M, against a similar antigenic epitope of human TRPM4. M4P and M4M demonstrated efficacy in mitigating stroke reperfusion injury. To facilitate human application, M4M was humanized through CDR grafting, resulting in human IgG1 antibodies (Ab1-6). These antibodies were evaluated for their binding affinity, surface staining, stability, and functional inhibition of the human TRPM4 channel. Ab6 (renamed as M4H) was selected and inhibited TRPM4 currents in human brain microvascular endothelial cells under ATP depletion conditions. Importantly, Ab6 (M4H) suppressed ATP depletion-induced cell swelling, indicating its potential for managing vascular injury in ischemic brain diseases. Future studies on animal models could advance the development of novel therapies of neurological disorders with vascular injury.

Pharmacodynamics of Glyburide, Metformin, and Glyburide/Metformin Combination Therapy in the Treatment of Gestational Diabetes Mellitus

In gestational diabetes mellitus (GDM), women are unable to compensate for the increased insulin resistance during pregnancy. Data are limited regarding the pharmacodynamic effects of metformin and glyburide during pregnancy. This study characterized insulin sensitivity (SI), β-cell responsivity, and disposition index (DI) in women with GDM utilizing a mixed-meal tolerance test (MMTT) before and during treatment with glyburide monotherapy (GLY, n = 38), metformin monotherapy (MET, n = 34), or GLY and MET combination therapy (COMBO; n = 36). GLY significantly decreased dynamic β-cell responsivity (31%). MET and COMBO significantly increased SI (121% and 83%, respectively). Whereas GLY, MET, and COMBO improved DI, metformin (MET and COMBO) demonstrated a larger increase in DI (P = 0.05) and a larger decrease in MMTT peak glucose concentrations (P = 0.03) than subjects taking only GLY. Maximizing SI with MET followed by increasing β-cell responsivity with GLY or supplementing with insulin might be a more optimal strategy for GDM management than monotherapy.

PPARγ Agonistic Activity of Sulphonylureas

BACKGROUND

Sulphonylureas (SU) are known to cause weight gain. Some investigators have reported increased insulin sensitivity with some sulphonylurea agents.

OBJECTIVE

To review available evidence of SU agents having PPARγ agonist activity.

METHODS

We searched online databases of PubMed®, Embase®, Google Scholar® and Web of Science® as per current guidance, published in English, between 1st January 1970 and 31st December 2017. The search found 6 articles.

RESULTS

None of the 1st generation SU drugs have any demonstrable PPARγ agonist activity. Most of the 2nd generation SU agents had a positive correlation between their concentration and PPARγ agonist activity except Gliclazide. The demonstrated PPARγ agonist activity was maximum in experiments with Glimepiride and Gliquidone and was seen in these in-vitro experiments at concentrations which were pharmacologically achievable in-vivo. The PPARγ agonist activity may be responsible for some sideeffect of the SU agents as weight gain. On the contrary, the clinical efficacy of the thiazolidinediones could theoretically be reduced when used in combination with the SUs with significant PPARγ agonist activity.

CONCLUSION

The PPARγ agonist activity demonstrated in vitro experiments may have clinical connotations.

Glibenclamide in patients with poorly controlled type 2 diabetes: a 12-week, prospective, single-center, open-label, dose-escalation study

BACKGROUND

The purpose of this study was to investigate the effect of glibenclamide dose escalation on blood glucose and insulin in patients with poorly controlled type 2 diabetes.

METHODS

Twenty-two subjects with type 2 diabetes were administered increasing doses (0, 2.5, 5, 10, and 20 mg/day) of glibenclamide at 2-week intervals. Glibenclamide, glucose, and insulin determinations were performed.

RESULTS

The decrease in mean blood glucose from zero dose was 20%, 22%, 26%, and 28% for doses of 2.5, 5, 10, and 20 mg/day, respectively, which was significant from zero dose to 2.5 mg/day (P≤0.001). There were no significant decreases in glucose concentration beyond 2.5 mg/day. The percentage increase in mean insulin from zero dose was 51%, 58%, 44%, and 33% for 2.5, 5, 10, and 20 mg/day respectively. Mean blood insulin increased significantly from zero dose to 2.5 mg/day (P≤0.001). There were no significant increases in mean insulin concentration beyond 2.5 mg/day.

CONCLUSION

The results of this study suggest that increasing doses of glibenclamide do not produce a proportional increase in insulin secretion or a proportional decrease in blood glucose concentration.

Sulfonylureas: a new look at old therapy

Sulfonylurea compounds were the first available oral antidiabetic agents and they remain an important tool in our quest for optimal glucose control. The sulfonylureas stimulate the release of insulin from pancreatic β-cells and have a number of extrapancreatic effects, including decreasing hepatic insulin clearance and reducing glucagon secretion in patients with type 2 diabetes. Although these agents have been the mainstay of pharmacotherapy for patients with type 2 diabetes mellitus (T2DM), their safety and clinical utility has been a matter of active debate in recent years, as their use is associated with risks of hypoglycemia and weight gain. We review the discovery and mechanisms of action of sulfonylureas, and the results of clinical trials to provide practical information on the pros and cons of their use in clinical practice. This review addresses advances in our understanding of mechanisms of action of sulfonylurea agents, their efficacy in T2DM, side effects, and impact on cardiovascular disease outcomes.

Comparative effectiveness of dipeptidyl peptidase-4 (DPP-4) inhibitors and human glucagon-like peptide-1 (GLP-1) analogue as add-on therapies to sulphonylurea among diabetes patients in the Asia-Pacific region: a systematic review

The prevalence of diabetes mellitus is rising globally, and it induces a substantial public health burden to the healthcare systems. Its optimal control is one of the most significant challenges faced by physicians and policy-makers. Whereas some of the established oral hypoglycaemic drug classes like biguanide, sulphonylureas, thiazolidinediones have been extensively used, the newer agents like dipeptidyl peptidase-4 (DPP-4) inhibitors and the human glucagon-like peptide-1 (GLP-1) analogues have recently emerged as suitable options due to their similar efficacy and favorable side effect profiles. These agents are widely recognized alternatives to the traditional oral hypoglycaemic agents or insulin, especially in conditions where they are contraindicated or unacceptable to patients. Many studies which evaluated their clinical effects, either alone or as add-on agents, were conducted in Western countries. There exist few reviews on their effectiveness in the Asia-Pacific region. The purpose of this systematic review is to address the comparative effectiveness of these new classes of medications as add-on therapies to sulphonylurea drugs among diabetic patients in the Asia-Pacific countries. We conducted a thorough literature search of the MEDLINE and EMBASE from the inception of these databases to August 2013, supplemented by an additional manual search using reference lists from research studies, meta-analyses and review articles as retrieved by the electronic databases. A total of nine randomized controlled trials were identified and described in this article. It was found that DPP-4 inhibitors and GLP-1 analogues were in general effective as add-on therapies to existing sulphonylurea therapies, achieving HbA1c reductions by a magnitude of 0.59-0.90% and 0.77-1.62%, respectively. Few adverse events including hypoglycaemic attacks were reported. Therefore, these two new drug classes represent novel therapies with great potential to be major therapeutic options. Future larger-scale research should be conducted among other Asia-Pacific region to evaluate their efficacy in other ethnic groups.

Are we optimizing gestational diabetes treatment with glyburide? The pharmacologic basis for better clinical practice

Glyburide's pharmacokinetics (PK) and pharmacodynamics have not been studied in women with gestational diabetes mellitus (GDM). The objective of this study was to assess steady-state PK of glyburide, as well as insulin sensitivity, beta-cell responsivity, and overall disposition indices after a mixed-meal tolerance test (MMTT) in women with GDM (n = 40), nonpregnant women with type 2 diabetes mellitus (T2DM) (n = 26), and healthy pregnant women (n = 40, MMTT only). At equivalent doses, glyburide plasma concentrations were approximately 50% lower in pregnant women than in nonpregnant subjects. The average umbilical cord/maternal plasma glyburide concentration ratio at the time of delivery was 0.7 +/- 0.4. Insulin sensitivity was approximately fivefold lower in women with GDM as compared with healthy pregnant women. Despite comparable beta-cell responsivity indices, the average beta-cell function corrected for insulin resistance was more than 3.5-fold lower in women with glyburide-treated GDM than in healthy pregnant women. Women with GDM in whom glyburide treatment has failed may benefit from alternative medication or dosage escalation; however, fetal safety should be kept in mind.

Kinetics-effect relations of insulin-releasing drugs in patients with type 2 diabetes: brief overview

Sulfonylureas and glinides have similar mechanisms of action but differ in receptor affinity and binding sites and in absorption and elimination rates. This promotes differences in potency, rate of onset, and duration of action. While prominent in single-dose studies, these differences have less importance during long-term sulfonylurea treatment: at ordinary dosages, rapid- and short-acting (glipizide) and slow- and long-acting (glyburide) sulfonylureas maintained continuously effective plasma levels and similar 24-h glucose control. Moreover, there was no difference in patient outcome between the first-generation sulfonylurea chlorpropamide and the second-generation glyburide in the U.K. Prospective Diabetes Study. However, the risk of long-lasting and hence dangerous hypoglycemia is higher with these two long-acting sulfonylureas. Conversely, this risk should be low with the short-acting glinides, but seemingly at the expense of less effective glucose control. The most important kinetics-effect relations are that hyperglycemia delays sulfonylurea absorption and that the sulfonylurea dose-response curve is bell shaped; continuous sulfonylurea exposure over a certain level (e.g., 10 mg glipizide) impairs rather than improves insulin and glucose responses to sulfonylurea (downregulation). Accordingly, a vicious circle may be established: unrelenting hyperglycemia may promote sulfonylurea dose increase, which increases hyperglycemia, promoting further dose increase and eventually therapeutic failure.

The role of sulphonylureas in the management of type 2 diabetes mellitus

The sulphonylureas act by triggering insulin release from the pancreatic beta cell. A specific site on the adenosine triphosphate (ATP)-sensitive potassium channels is occupied by sulphonylureas leading to closure of the potassium channels and subsequent opening of calcium channels. This results in exocytosis of insulin. The meglitinides are not sulphonylureas but also occupy the sulphonylurea receptor unit coupled to the ATP-sensitive potassium channel. Glibenclamide (glyburide), gliclazide, glipizide and glimepiride are the primary sulphonylureas in current clinical use for type 2 diabetes mellitus. Glibenclamide has a higher frequency of hypoglycaemia than the other agents. With long-term use, there is a progressive decrease in the effectiveness of sulphonylureas. This loss of effect is the result of a reduction in insulin-producing capacity by the pancreatic beta cell and is also seen with other antihyperglycaemic agents. The major adverse effect of sulphonylureas is hypoglycaemia. There is a theoretical concern that sulphonylureas may affect cardiac potassium channels resulting in a diminished response to ischaemia. There are now many choices for initial therapy of type 2 diabetes in addition to sulphonylureas. Metformin and thiazolidinediones affect insulin sensitivity by independent mechanisms. Disaccharidase inhibitors reduce rapid carbohydrate absorption. No single agent appears capable of achieving target glucose levels in the majority of patients with type 2 diabetes. Combinations of agents are successful in lowering glycosylated haemoglobin levels more than with a single agent. Sulphonylureas are particularly beneficial when combined with agents such as metformin that decrease insulin resistance. Sulphonylureas can also be given with a basal insulin injection to provide enhanced endogenous insulin secretion after meals. Sulphonylureas will continue to be used both primarily and as part of combined therapy for most patients with type 2 diabetes.

Potential Cholestatic Activity of Various Therapeutic Agents Assessed by Bile Canalicular Membrane Vesicles Isolated from Rats and Humans

The active transport of solutes mediated by the bile salt export pump (BSEP/ABCB11) and multidrug resistance associated protein-2 (MRP2/ABCC2) are thought to involve bile acid-dependent and -independent bile formation, respectively. To evaluate the potential of therapeutic agents as inhibitors of such transporters on bile canalicular membranes, we examined the inhibition of the primary active transport of typical substrates by 15 drugs, clinically known to cause cholestasis in canalicular membrane vesicles. The inhibition by most of the compounds in rat canalicular membrane vesicles (CMVs) was minimal or observed at much higher concentrations than obtained in clinical situations. However, cloxacillin, cyclosporin A and midecamycin inhibited BSEP, and cyclosporin A and midecamycin inhibited MRP2 with an inhibition constant close to the clinical concentration. By comparing the inhibition potential between rat and human CMVs, the inhibition of BSEP- and MRP2-mediated transport by midecamycin and cyclosporin A was relatively similar whereas the inhibitory effect on BSEP-mediated transport by cloxacillin and glibenclamide was more marked in humans than in rats. These results suggest that the majority of cholestasis-inducing drugs have a minimal inhibitory effect on rat BSEP and MRP2 although species differences in inhibitory potential should be considered, especially in the case of BSEP.

Glyburide/Glipizide Combination Therapy in Type 2 Diabetes

Objective

Research has determined differences in the pharmacokinetics and therapeutic actions of glyburide and glipizide. The goal of this study was to evaluate the hypoglycemic effects of glyburide/glipizide combination therapy in the management of patients with diabetes not adequately controlled on either agent alone.

Methods

Nine patients (3 men, mean age 50.6 ± 11 y) who were hyperglycemic on either glyburide or glipizide monotherapy continued their previous regimen with doses titrated up to maximum daily doses and dietary therapy for 4 weeks, and then they were placed on morning glipizide/evening glyburide combination therapy for 12 weeks.

Results

Combination therapy had no significant effect on glycemic control; no differences in glycosylated hemoglobin (HbAIC) were observed (baseline, 15.3% ± 3.6%; monotherapy, 14.8% ± 3.3%; combination, 13.4% ± 3.5%). However, during combined glyburide/glipizide therapy, fasting plasma glucose was significantly reduced by 53.4 ± 20.0 mg/dL in young (age <50 y) and increased by 73.7 ± 26.9 mg/dL in older subjects. HbAIC was reduced by 3.8% ± 4.0% in young and increased by 1.7% ± 1.3% in older subjects. No significant changes in blood pressure, body weight, or lipid parameters occurred.

Conclusions

Our preliminary data indicate the limited usefulness of combined glyburide/glipizide therapy. The modest reduction in hyperglycemia observed in patients younger than 50 years of age warrant future studying.

Effects and serum levels of glibenclamide and its active metabolites in patients with type 2 diabetes

OBJECTIVE

To study the effects and serum levels of glibenclamide (Gb) and its active metabolites in patients on chronic Gb medication on different daily doses.

MATERIAL AND METHODS

Fifty patients with type 2 diabetes on regular Gb therapy (1.75-14.0 mg daily). Blood samples were taken immediately before and 90 min after regular Gb intake. A standardized breakfast was served 30 min after drug intake. Serum insulin and proinsulin levels were determined by ELISA methods without cross-reactivities. Serum drug levels were determined by HPLC. Fischer's R to Z-test (correlation coefficients) and paired Student t-tests were used when comparing values within the entire group and unpaired non-parametric Mann-Whitney tests were used when comparing high and low dose levels. A p-value < 0.05 was considered significant.

RESULTS

There were significant correlations between daily Gb dose, on the one hand, and, on the other, HbAlc (r = 0.55), Delta-insulin (r = - 0.59) and Delta-proinsulin (r = - 0.52) levels. Significant correlations between Gb therapy duration and insulin (r = - 0.40) and proinsulin (r = - 0.34) secretion and between Gb dose and ratio proinsulin/insulin (RPI) at both time points (r = 0.32 and 0.30) were also found. The RPI was lower after Gb intake. In patients on > or = 10.5 mg steady state serum metabolite levels (Ml and Ml + M2) were higher (29(0-120) and 33 (0-120) ng/ml) than those of Gb itself (18(0-64) ng/ml). A great inter-subject variability in Gb levels at both time points was seen.

CONCLUSIONS

Our results indicate that, in patients on chronic medication, Gb is capable of stimulating both insulin and proinsulin secretion; the effect on insulin release is relatively greater. The effect was more pronounced in patients on a low Gb dose, either because of less impaired beta-cells in those receiving low doses, or due to reduced sulphonylurea sensitivity in those on high dosage (down-regulation). In patients on a daily dose of 10.5 mg or more, serum metabolite levels of clinical relevance were demonstrated; the metabolites may contribute to hypoglycaemic events.

Comparative tolerability of sulphonylureas in diabetes mellitus

The sulphonylurea drugs have been the mainstay of oral treatment for patients with diabetes mellitus since they were introduced. In general, they are well tolerated, with a low incidence of adverse effects, although there are some differences between the drugs in the incidence of hypoglycaemia. Over the years, the drugs causing the most problems with hypoglycaemia have been chlorpropamide and glibenclamide (glyburide), although this is a potential problem with all sulphonylureas because of their action on the pancreatic beta cell, stimulating insulin release. Other specific problems have been reported with chlorpropamide that occur only rarely, if at all, with other sulphonylureas. Hyponatraemia secondary to inappropriate antidiuretic hormone activity, and increased flushing following the ingestion of alcohol, have been well described. The progressive beta cell failure with time results in eventual loss of efficacy, as these agents depend on a functioning beta cell and are ineffective in the absence of insulin-producing capacity. Differences in this secondary failure rate have been reported, with chlorpropamide and gliclazide having lower failure rates than glibenclamide or glipizide. The reasons for this are unclear, but the more abnormal pattern of insulin release produced by glibenclamide may be partly responsible and, indeed, may explain the increased risk of hypoglycaemia with this agent. Previously reported increased mortality associated with tolbutamide therapy has not been substantiated, and more recent data have shown no increased mortality from sulphonylurea treatment. Indeed, benefit from glycaemic control, regardless of the agent used--insulin or sulphonylurea--was reported by the United Kingdom Prospective Diabetes Study. Nevertheless, there is still ongoing controversy in view of the experimental evidence, mainly from animal studies, of potential adverse effects on the heart from sulphonylureas, but these are difficult to extrapolate into clinical situations. Most of these studies have been carried out with glibenclamide, which makes comparison of possible risk difficult. Other cardiovascular risk factors may be modified by gliclazide, which seems unique among the sulphonylureas in this respect. Its reported haemobiological and free radical scavenging activity probably resides in the azabicyclo-octyl ring structure in the side chain. Reduced progression or improvement in retinopathy has been reported in comparative trials with other sulphonylureas, and the effect is unrelated to improvements in glycaemia. There are differences between the sulphonylureas in some adverse effects, risk of hypoglycaemia, failure rates and actions on vascular risk factors. As a group of drugs, they are very well tolerated, but differences in overall tolerability can be identified.

Comparative efficacy and potency of long-term therapy with glipizide or glyburide in patients with type 2 diabetes mellitus

BACKGROUND

Long-term studies on the comparative efficacy and relative potency of glipizide and glyburide are sparse and controversial.

METHODS

In a randomized prospective trial, we compared the effectiveness and relative potency of glipizide and glyburide over a 15-month period in 18 patients with type 2 diabetes mellitus (DM2) (9 on glyburide and 9 on glipizide) who were unresponsive to diet therapy. Glycemic control was assessed using 4 methods: 1) quarterly fasting plasma glucose (FPG), and 2-hour postprandial plasma glucose after a standard breakfast; 2) insulin and glucose response to Sustacal (test meal) challenge every 3 to 6 months; 3) quarterly hemoglobin A1c; and 4) intravenous glucose tolerance testing every 6 months to measure first and second phase insulin secretion. Patient characteristics were similar in each treatment group.

RESULTS

Similar doses of glipizide (11 mg/day) or glyburide (10 mg/day) resulted in comparable reduction of FPG and hemoglobin A1c and increase in first phase insulin response to intravenous glucose tolerance testing. There was greater reduction in FPG and 2-hour postprandial plasma glucose with glipizide than with glyburide in 6 months. Contrary to the Physicians' Desk Reference, but consistent with another short-term study, our long-term study demonstrated that glipizide and glyburide are equipotent at similar doses in controlling hyperglycemia in DM2.

CONCLUSIONS

Glipizide and glyburide are effective in controlling hyperglycemia with similar doses in DM2. Glipizide exhibits greater reduction in FPG and 2PPG at 6 months. Additional studies are needed to validate equipotency of these drugs.

Pharmacologic therapy for type 2 diabetes mellitus

Type 2 diabetes mellitus is a chronic metabolic disorder that results from defects in both insulin secretion and insulin action. An elevated rate of basal hepatic glucose production in the presence of hyperinsulinemia is the primary cause of fasting hyperglycemia; after a meal, impaired suppression of hepatic glucose production by insulin and decreased insulin-mediated glucose uptake by muscle contribute almost equally to postprandial hyperglycemia. In the United States, five classes of oral agents, each of which works through a different mechanism of action, are currently available to improve glycemic control in patients with type 2 diabetes. The recently completed United Kingdom Prospective Diabetes Study (UKPDS) has shown that type 2 diabetes mellitus is a progressive disorder that can be treated initially with oral agent monotherapy but will eventually require the addition of other oral agents, and that in many patients, insulin therapy will be needed to achieve targeted glycemic levels. In the UKPDS, improved glycemic control, irrespective of the agent used (sulfonylureas, metformin, or insulin), decreased the incidence of microvascular complications (retinopathy, neuropathy, and nephropathy). This review examines the goals of antihyperglycemic therapy and reviews the mechanism of action, efficacy, nonglycemic benefits, cost, and safety profile of each of the five approved classes of oral agents. A rationale for the use of these oral agents as monotherapy, in combination with each other, and in combination with insulin is provided.

Is there a concentration-effect relationship for sulphonylureas?

Sulphonylureas have remained the mainstay of oral therapy for type 2 (non-insulin-dependent) diabetes mellitus (NIDDM). They stimulate insulin release from pancreatic beta cells. Pharmacokinetic differences between the various sulphonylureas are of clinical importance in terms of the time to onset of action, timing of drug administration in relation to food intake, magnitude and duration of the glucose-lowering effect and the risk of serious hypoglycaemia. Recent studies with improved analytical sensitivity have shown that the elimination half-life of glibenclamide is longer than previously thought and that 2 metabolites of glibenclamide have significant hypoglycaemic activity. Furthermore, single dose studies in healthy volunteers using an integrated pharmacokinetic-pharmacodynamic model have identified clear concentration-effect relationships for both glibenclamide and its metabolites after oral and intravenous administration. Under multiple dose conditions, kinetic-dynamic relations have been identified with shorter-acting drugs in dosages that give discontinuous sulphonylurea exposure. However, at continuous exposure, i.e. sustained 24-hour therapeutic concentrations in plasma, there is evidence indicating the development of tolerance, which may be caused by downregulation of beta cell sensitivity. As more sophisticated concentration-effect studies appear, it has become evident that currently recommended maximum daily doses of many sulphonylureas are too high.

The effects of obesity on the pharmacokinetics and pharmacodynamics of glipizide in patients with non-insulin-dependent diabetes mellitus

The pharmacokinetics and pharmacodynamics of glipizide were evaluated in 20 patients with non-insulin-dependent diabetes mellitus (NIDDM). The group consisted of 12 obese subjects (seven women, five men; mean +/- SD age, 53.5 +/- 8.5 years; total body weight (TBW), 95.5 +/- 17.2 kg; percentage > IBW (ideal body weight), 57.8 +/- 31.7%); and eight nonobese subjects (two women, six men; age, 57.8 +/- 11.7 years; TBW, 80.8 +/- 9.9 kg; percentage > IBW, 15.6 +/- 10.3%). After a 2-week antidiabetic drug-free period, patients were started on glipizide therapy for 12 weeks. Glipizide dosages were titrated to achieve specified therapeutic goals or a maximum daily dose of 40 mg. Glipizide pharmacokinetics were assessed by serum concentrations obtained during a 24-h pharmacokinetic evaluation performed after the first 5-mg dose (SD) and after 12 weeks of chronic therapy (CD). Glipizide pharmacodynamics were evaluated with serum glucose, insulin, and C-peptide responses to Sustacal tolerance test done at baseline, after SD, and after CD. No statistically significant differences in the SD pharmacokinetic parameters (Tmax = 3.1 +/- 1.2 vs. 2.8 +/- 1.6 h; Cmax = 332.5 +/- 92.5 vs. 420.8 +/- 142 g/L; area under the curve extrapolated to infinity (AUCI) = 2,598.3 +/- 1,148 vs. 3,138.9 +/- 1,847 g/h/L; oral clearance/bioavailability (CL/F), 2.3 +/- 1.0 vs. 2.0 +/- 1.0 L/h; volume of distribution/bioavailability (V/F), 19.5 +/- 4.4 vs. 17.2 +/- 4.3 L; t1/2 = 5.0 +/- 2.3 vs. 5.2 +/- 2.0 h) were observed between the obese and nonobese groups, respectively. The pharmacokinetic parameters assessed under CD conditions were also closely matched in the two groups. No differences in glucose responses to Sustacal challenge at baseline, SD, and CD (AUC0-->4.glucose:baseline, 52.3 +/- 18.0 vs. 44.9 +/- 9.8; SD, 50.4 +/- 20.9 vs. 36.1 +/- 11.0; CD, 37.8 +/- 10.7 vs. 36.6 +/- 8.5 mM/h) were noted between the obese and nonobese groups, respectively. However, glucose concentrations increased more and decreased to a smaller extent after SD in the obese as compared to nonobese subjects. Mean fasting serum insulin and C-peptide concentrations were not statistically different between the two groups. However, obese subjects exhibited higher fasting insulin (114.0 +/- 69 vs. 68.8 +/- 52 pM) at week 12 evaluation and C-peptide concentrations (0.83 +/- 0.2 vs. 0.63 +/- 0.2 nM) after SD as compared to the nonobese group. A smaller percentage increase in C peptide in response to Sustacal challenge was observed in the obese compared to the nonobese subjects (baseline, 60 +/- 25 vs. 117 +/- 117; SD, 119 +/- 39 vs. 193 +/- 149; and CD, 97 +/- 56 vs. 163 +/- 67%). In summary, the influence of obesity on glipizide pharmacokinetics appeared to be of little clinical significance. The observed differences in pharmacodynamics require further evaluation.

Metformin: an antihyperglycemic agent for treatment of type II diabetes

OBJECTIVE

To review the comparative efficacy of metformin, sulfonylureas, and insulin in the treatment of patients with type II diabetes.

DATA SOURCES

Articles were identified by a MEDLINE search of articles from 1966 to 1994, using the terms metformin, sulfonylurea, chlorpropamide, glipizide, glyburide, tolazamide, tolbutamide, and insulin, published in English, French, or German. Articles also were identified from bibliographies of pertinent articles.

STUDY SELECTION

With the exception of articles dealing with the pharmacology of metformin, only randomized, active, controlled studies were selected for review.

DATA EXTRACTION

Effects of metformin therapy on metabolic and cardiovascular risk factors were abstracted: weight, blood pressure, total and low-density lipoprotein cholesterol, triglycerides, fasting and postprandial glucose, and glycosylated hemoglobin.

DATA SYNTHESIS

Metformin is an antihyperglycemic agent with a mean bioavailability of 50-60%. It is eliminated primarily by renal filtration and secretion and has a half-life of approximately 6 hours in patients with type II diabetes. Although the half-life of metformin is prolonged in patients with renal impairment, no specific dosage adjustments have been recommended. This agent has no effect in the absence of insulin. Metformin is as effective as the sulfonylureas in treating patients with type II diabetes and has a more prominent postprandial effect than the sulfonylureas or insulin. When combined with a sulfonylurea, metformin has been shown to exert antihyperglycemic effects in addition to the sulfonylurea with which it is combined. Metformin decreases absorption of vitamin B12 and folic acid, although reported cases of megaloblastic anemia are rare. Cimetidine decreases the elimination of metformin; therefore, the manufacturer reccommends a reduced metformin dosage when these agents are combined. The most frequently reported adverse effects of metformin are gastrointestinal in nature (diarrhea, nausea, abdominal pain, and metallic taste, in decreasing order). Metformin has been used in Canada, Great Britain, and the rest of Europe for more than 30 years and was approved for use in the US in December 1994.

CONCLUSIONS

Three trials comprise the Food and Drug Administration approval database (one foreign). Metformin will be most useful in managing patients with poorly controlled postprandial hyperglycemia, as its postprandial effect is much greater than that of the sulfonylureas. In contrast, sulfonylureas or insulin are more effective for managing patients with poorly controlled fasting hyperglycemia. Metformin should be considered a first-line agent, particularly in obese or hyperlipidemic patients.

A novel mechanism of glipizide sulfonylurea action: decreased metabolic clearance rate of insulin

To examine whether sulfonylureas inhibit the metabolic clearance rate (MCR) of insulin, 19 healthy young subjects participated in two experiments. In the first protocol (n = 10), a 3-h oral glucose load was performed with and without 2 mg of glipizide given 30 min before glucose ingestion. The total insulin response was 60% greater with than without glipizide (5.9 +/- 0.6 vs 3.7 +/- 0.5 microU/ml; P < 0.001). However, the total C-peptide responses were virtually identical (4.7 +/- 0.5 vs 4.8 +/- 0.4 nmol/l) in both studies. In the second protocol (n = 9), the MCR of insulin was measured during 4-h euglycemic insulin clamps performed with and without glipizide. In the study with glipizide, the subjects ingested 5 mg of glipizide at 120 min. The steady-state plasma insulin concentration during the 4th h, i.e., 1-2 h after glipizide ingestion, was significantly higher than during the 2nd h, i.e., before glipizide ingestion (99 +/- 22 vs 78 +/- 17 microU/ml; P < 0.01). In addition, glucose uptake during the 4th h was greater (8.0 +/- 1.6 vs 6.4 +/- 1.5 mg/kg.min) and the MCR of insulin was reduced (503 +/- 126 vs 621 +/- 176 ml/m2.min; P < 0.01). We conclude that glipizide augments plasma insulin levels both by enhancing its secretion and by decreasing the MCR of insulin.

Increase in insulin binding and inhibition of the decrease in the phospholipid content of human term placental homogenates in culture by the sulfonylurea glipizide

Term placental explants were cultivated for 48 hr without (control) and with various concentrations of glipizide. Maximum binding of [125I]-insulin in the control samples was decreased after 12 and 24 hr returning to initial values after 48 hr. In the presence of glipizide the binding was generally higher, reaching 180% (557 and 1000 nmol/L) of the corresponding control value (P < 0.01) after 48 hr owing to the presence of nearly 3-fold more (P < 0.05) receptors than in the untreated controls. Tissue cholesterol content was almost unaffected whereas both the phospholipid content and the corresponding phospholipid-to-cholesterol ratios were markedly, and in a time-dependent manner, increased by glipizide as compared to the controls. This was due to decreasing cholesterol and phospholipid concentrations in the controls during the time of culture as compared to initial values, and also to unchanged levels in glipizide-treated cultures. We conclude that glipizide affects placental insulin receptors and the phospholipid content of the tissue.

The acute effect of preprandial exogenous and endogenous sulphonylurea-stimulated insulin secretion on postprandial glucose excursions in patients with type 2 diabetes

Sulphonylureas improve glucose tolerance by stimulating insulin secretion. Whether improved glucose tolerance results from enhanced early insulin release or greater total insulin secretion is not clear. Insulin response to a test meal in Type 2 diabetic subjects with and without a single dose (2.5 mg) of oral and intravenous glipizide were, therefore, measured. Intravenous glipizide enhanced early insulin release more than oral glipizide (134% and 80% vs control; p < 0.01), whereas total insulin release was equally improved (78% and 54% vs control; p < 0.01). Despite slight differences in insulin release, there was no difference in glucose tolerance (median area under concentration curve (AUC); 66.6 vs 61.9 mmol x min l-1; NS). The test meal was repeated after a bolus of intravenous insulin at the beginning of the meal. This allowed comparison of the effect of exogenous and endogenous insulin supply on postprandial glucose excursions. In spite of an early and fivefold larger rise in serum insulin after intravenous administration of the hormone than after intravenous glipizide (725% vs 134%; p < 0.01), postprandial glucose was no better than after glipizide (median AUC; 87.8 vs 66.6 mmol x min l-1; NS). In contrast, glucose tolerance was better after oral glipizide compared to intravenous insulin (median AUC; 61.9 vs 87.8 mmol x min l-1; p < 0.05). In conclusion, the total amount of insulin secreted seems more important than the timing of the insulin release for the postprandial glucose tolerance in Type 2 diabetic subjects. Neither endogenous nor peripheral premeal supply of insulin could normalize postprandial glucose excursions in patients with Type 2 diabetes.

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)

The relationship between early insulin release and glucose tolerance in healthy subjects

Sulphonylureas improve glucose tolerance by stimulating insulin secretion. Whether improved glucose tolerance results from enhanced early insulin release or greater total insulin secretion is not clear. Therefore insulin and C-peptide responses to oral glucose were measured in healthy subjects with and without a single dose of oral and intravenous glipizide. The intravenous glipizide administration caused a marked early insulin response, whereas oral glipizide administration resulted in greater total and peak insulin concentration. Oral glipizide did not reduce plasma glucose until 45 min of the glucose load. In contrast, enhancement of the early insulin response with intravenous glipizide almost completely prevented postprandial glucose rise. In conclusion, early insulin release is a major factor determining oral glucose tolerance in healthy subjects.

The role of plasma non-esterified fatty acids during exercise in type 2 diabetes mellitus

Elevated fasting plasma non-esterified fatty acid (NEFA) levels have been reported in Type 2 diabetes. We examined whether such changes persist during low-grade exercise and influence carbohydrate metabolism. Eight Type 2 diabetic patients with moderate glycaemic control and eight healthy controls received the anti-lipolytic agent, acipimox, or placebo on separate occasions before exercising for 45 min at 35% pre-determined VO2max. Fasting plasma NEFA levels were similar (0.40 +/- 0.06 (SEM) and 0.45 +/- 0.05 mmol l-1; healthy and Type 2 diabetic subjects) following placebo, and increased to comparable levels with exercise (0.73 +/- 0.07 and 0.73 +/- 0.10 mmol l-1). Acipimox lowered basal NEFA levels (0.14 +/- 0.03 and 0.28 +/- 0.04 mmol l-1; both p < 0.05 vs placebo), and prevented the rise with exercise. Blood glucose (p < 0.001) and serum insulin (p < 0.01) levels were higher in the Type 2 diabetic patients (vs controls) for both treatments. Whole body lipid oxidation increased from baseline to a comparable degree with exercise following placebo (3.2 +/- 0.3 and 2.8 +/- 0.3 mg kg-1 min-1; healthy and Type 2 diabetic subjects, both p < 0.02). Although less marked, the same was also observed following acipimox (2.0 +/- 0.4 and 2.1 +/- 0.5 mg kg-1 min-1; both p < 0.05). Carbohydrate oxidation increased with exercise in both subject groups, but with no significant difference between the treatments. Thus, the metabolic response to low-grade exercise was normal in Type 2 diabetic patients with moderate glycaemic control, but occurred against a background of hyperinsulinaemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Inappropriate use of high-dose glyburide to treat uncontrolled type 2 diabetes mellitus

OBJECTIVE

To report a case of chronic glyburide overdose.

CASE SUMMARY

A patient with noninsulin-dependent diabetes mellitus (NIDDM) who had previously developed secondary failure while taking a maximal dosage of glipizide was switched to glyburide 5 mg/d. The patient initially experienced adequate glycemic control while taking glyburide, but subsequently experienced deterioration in glycemic control. This necessitated gradual increases in the dosage of glyburide until the maximum dosage of 20 mg/d was reached. Because the patient's diabetic control did not improve with this dosage of glyburide, she decided independently to increase the dosage further. She ingested an average daily dose of 37.7 mg of glyburide over the 18 days that preceded her clinic visit without experiencing any glyburide-related adverse effects.

DISCUSSION

Progression of NIDDM may be responsible for the development of secondary sulfonylurea failure in NIDDM patients treated with oral sulfonylurea drugs. Consequently, these patients should be treated as patients dependent on insulin.

CONCLUSIONS

NIDDM patients treated with oral sulfonylurea drugs require long-term blood glucose monitoring to detect the development of secondary sulfonylurea failure. Patients who experience secondary failure to a particular sulfonylurea drug do not appear to develop long-term blood glucose control when switched to a different oral sulfonylurea drug. These patients should be treated with insulin therapy.

Evaluation of glipizide and glyburide in a health maintenance organization

OBJECTIVE

To determine if there was a difference in the long-term glycemic control, average daily dose, and cost of therapy in patients with noninsulin-dependent diabetes mellitus (NIDDM) treated with glyburide and glipizide in a health maintenance organization (HMO).

DESIGN

Retrospective evaluation of medical and pharmacy records.

SETTING

Multispecialty group practice HMO.

PATIENTS

140 NIDDM patients being treated with either glyburide (n = 70) or glipizide (n = 70) were randomly selected from the populations of patients receiving either drug using computerized pharmacy records.

MAIN OUTCOME MEASURE

Mean daily doses and blood glucose measurements (fasting blood glucose, random blood glucose, hemoglobin A1C) were stratified in 3-month periods from the time the drug therapy was started or the patient first presented to the clinic for a total of 18 months. Long-term glycemic control was defined as fasting blood glucose less than 8.33 mmol/L (150 mg/dL).

RESULTS

The groups were comparable with regard to age (53.4 y glyburide, 56.7 y glipizide), gender (43 M:27 F glyburide, 47 M:23 F glipizide), race (38 W/16 B/16 H glyburide, 45 W/16 B/9 H glipizide), concurrent medical conditions, adverse effects, and compliance. Long-term glycemic control was similar in both groups. Although the number of subjects who were controlled (by definition) tended to be greater in the glyburide group, no clinical or statistical difference was found. There was no statistical difference in mean daily dose between the ethnic groups, but the small numbers preclude further analysis. The glipizide group had a larger percentage increase in dose within the first year than did the glyburide group; however, the percentage increase from the 3-month dose was similar after 18 months (22.7 percent glyburide, 27.5 percent glipizide.) Average daily cost of therapy, based on mean daily dose, was slightly lower for glyburide-treated patients.

CONCLUSIONS

If glycemic control is similar with glyburide and glipizide, as seen in this study, economic considerations regarding choice of therapy and formulary inclusion may be appropriate.

Glipizide-induced immunomodulation: inhibition of human mononuclear cell stimulation and macrophage-mediated islet cell killing in the BB rat

Intensive insulin treatment, when combined with sulfonylurea drugs, may enhance remissions in new-onset type I diabetic patients. These clinical data suggest that sulfonylurea drugs may have immunosuppressive actions in addition to insulin secretory and sensitivity actions. Thus, studies were conducted in humans to determine if glipizide was immunomodulatory in vitro. Five, 10, and 15 micrograms/mL of phytohemagglutinin (PHA) and concanavalin A (Con A), and 0.5, 1.0, and 1.5 micrograms/mL of pokeweed mitogen (PWM) were incubated with normal human peripheral blood mononuclear cells. Maximum stimulatory indices were 52, 39, and 30 for PHA, Con A, and PWM, respectively. Additional incubations were performed in the presence of 1, 10(1), 10(2), 10(3), 10(4), and 10(5) ng/mL glipizide. Glipizide concentrations inhibiting mitogen stimulation approximately 50% (P less than .01 v nonglipizide control) were 1.0 ng/mL for PWM, 10 ng/mL for Con A, and 10(4) ng/mL for PHA. At higher glipizide levels, inhibition was 90% to 100%. To determine if glipizide immunomodulates diabetes-associated reactions, bio-breeding (BB) diabetic rat splenic macrophage-mediated islet killing was studied. Glipizide at 10(3) ng/mL inhibited islet killing by 60% (P less than .001). These preliminary data suggest that glipizide may have immunomodulatory actions not previously appreciated, and may be related to this drug's putative action in islet cell restoration.

Long-term effects of glipizide on insulin secretion and blood glucose control in patients with non-insulin-dependent diabetes mellitus

Of 23 patients with non-insulin-dependent diabetes mellitus (NIDDM), whose fasting blood glucose had not reached less than or equal to 6.0 mmol.l-1 after 10 weeks of dietary regulation, 15, who had had a weight reduction of -2.8 kg by dietary control, did achieve a fasting blood glucose less than or equal to 6.0 mmol.l-1 after addition of less than or equal to 20 mg glipizide daily. They had a sustained (greater than or equal to 2 years) increase in meal-induced insulin secretion (32% increase in postprandial C-peptide AUC), and a sustained reduction in postprandial hyperglycaemia (34% reduction in AUC). Ten of the patients took a mean daily dose less than 5 mg (4.8 mg) and had a sustained increase in insulin secretion rate (increased C-peptide slope). The 15 patients had no elevation of basal insulin secretion and no impairment of weight reduction. The remaining 8 subjects, who showed little or no weight reduction on dietary control, had little or no reduction in fasting blood glucose despite long-term treatment with 20 mg glipizide daily, a less sustained increase in meal-induced insulin secretion, a smaller reduction of postprandial hyperglycaemia, and an increase in body weight. On diagnosis the 8 subjects did not differ from the other 15 subjects in age, body weight, blood glucose, HbA1c, C-peptide or insulin, nor in their glucose and insulin responses to a test dose of glipizide; the main reason for the apparent drug failure appeared to be deficient compliance with dietary regulation rather than a primary inability to respond to sulphonylurea treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Management of non-insulin-dependent diabetes mellitus

The initial management of non-insulin-dependent diabetes mellitus (NIDDM) should include patient education, dietary counselling and, when feasible, individualised physical activity. It is only when such measures fail that drug therapy should be considered. Dietary management of NIDDM includes a restriction in calories, and these should be appropriately distributed as carbohydrates, lipids and proteins. Supplementation of the diet with soluble fibre and supplementation with magnesium salts if hypomagnesaemia is demonstrated, is recommended. However, supplementation with fish oils or with fish oil-derived omega-3 fatty acids is not currently recommended. Oral drug therapies used in NIDDM include sulphonylurea derivatives, which are a first-line treatment in patients who are not grossly obese, metformin, which is the treatment of choice for obese patients, and alpha-glucosidase inhibitors such as acarbose, which are used mainly to reduce postprandial blood glucose peaks. These types of drugs can be used alone or in combination. Insulin therapy may be required to achieve adequate control of blood glucose levels in some patients. In several instances, it is suggested that insulin therapy be combined with sulphonylureas (essentially when residual insulin secretion is present), with metformin, or with alpha-glucosidase inhibitors. The treatment of disorders associated with NIDDM, such as obesity, hypertension or hyperlipidaemia, requires particular attention in diabetic patients, since some drugs can adversely affect glycaemic control. Oral drugs for the treatment of NIDDM include sulphonylurea derivatives used in first-line treatment in patients who are not grossly obese, metformin, which is often the treatment of choice for obese patients and, more recently, the alpha-glucosidase inhibitors, such as acarbose, which are effective in reducing the postprandial rise in blood glucose.

Severe hypoglycaemia during treatment with glipizide

In the years 1980-87, 19 cases of severe hypoglycaemia during treatment of Type 2 diabetes with glipizide were reported to the Swedish Adverse Drug Reactions Advisory Committee. Patient age was 75 +/- 9 years (mean +/- SD) (significantly higher than in all patients on glipizide in Sweden), and the duration of glipizide treatment ranged from 1 day to 4 years. Eleven patients presented with coma, three with reduced consciousness and five with other symptoms. An uneventful early recovery occurred in 14 patients. The remaining five patients had prolonged or recurrent hypoglycaemia for up to 60 h. Two of the patients, both with complicating disorders, died. In a case-control substudy, patients with glipizide-associated hypoglycaemia were found to have renal impairment more often than age- and sex-matched controls treated with glipizide (odds ratio 4.0). The median dose of glipizide (10 mg per day) was identical to that in controls. Other drugs, notably diuretics and benzodiazepines, were more commonly used by hypoglycaemic patients (median 5 vs 2 concomitant drugs, p less than 0.001). We conclude that the use of glipizide is associated with a risk of developing severe hypoglycaemia with a clinical course that is not always benign.

Chronic exposure to glibenclamide impairs insulin secretion in isolated rat pancreatic islets

We investigated the effect of 24 h exposure to 100 nmol/l glibenclamide on insulin secretion in isolated rat pancreatic islets. The insulin content was similar in control islets and in islets preincubated with 100 nmol/l glibenclamide for 24 h. In islets preexposed to glibenclamide: 1) the subsequent response to a maximal glibenclamide stimulatory concentration (10 mumol/l, 1 h at 37 C) was greatly reduced in comparison to control islets (0.69 +/- 0.20% vs 2.16 +/- 0.41%; mean +/- SE; n = 14; p less than 0.001); 2) the response to 100 mumol/l tolbutamide stimulation was also reduced (0.55 +/- 0.15% vs 2.38 +/- 0.44%; n = 8; p less than 0.001); 3) the response to 16.7 mmo/l glucose, both in the presence or in the absence of 1 mmol/l IBMX, a phosphodiesterase inhibitor, was also diminished by about 50% (1.79 +/- 0.39% vs. 3.22 +/- 0.42%; n = 14, p less than 0.001). In glibenclamide pretreated islets, blunted responses to stimuli were confirmed also by dynamic studies using a perifusion system. The effect of glibenclamide preincubation was fully reversible: when islets cultured in the presence of glibenclamide were transferred to a glibenclamide-free medium for further 24 h, insulin release in response to glibenclamide stimulation returned to control values. We conclude that prolonged exposure of rat pancreatic islets to glibenclamide induces a reversible desensitization to a variety of metabolic stimuli. The inhibition by prolonged glibenclamide exposure of a common pathway in the mechanism of insulin release is one possible explanation for these results.

Effect of sulphonylurea on glucose-stimulated insulin secretion in healthy and non-insulin dependent diabetic subjects: a dose-response study

The effect of a rapid-acting sulphonylurea, glipizide, on the dose-response relationship between the beta-cell response (insulin and C-peptide secretion) and the ambient plasma glucose concentration was examined in 12 healthy and 6 non-insulin-dependent diabetic subjects. The subjects participated in two sets of experiments which were performed in random order: (A) four hyperglycaemic clamp studies, during which the plasma glucose concentration was raised for 120 min by 1 (only in healthy subjects), 3, 7, and 17 mmol/l; and (B) the same four hyperglycaemic clamp studies preceded by ingestion of 5 mg glipizide. All subjects participated in a further study, in which glipizide was ingested and the plasma glucose concentration was maintained at the basal level. In control subjects in the absence of glipizide, the first-phase plasma insulin response (0-10 min) increased progressively with increasing plasma glucose concentration up to 10 mmol/l, above which it tended to plateau. Glipizide augmented the first-phase insulin response without changing the slope of the regression line relating plasma insulin to glucose concentrations. The second-phase plasma insulin response (20-120 min) increased linearly with increasing hyperglycaemia (r = 0.997). Glipizide alone increased the plasma insulin response by 180 pmol/l. A similar increase in plasma insulin response following glipizide was observed at each hyperglycaemic step, indicating that glipizide did not affect the sensitivity of the beta-cell to glucose. First-phase insulin secretion was reduced in the type 2 (non-insulin-dependent) diabetic patients, and was not influenced by glipizide.(ABSTRACT TRUNCATED AT 250 WORDS)

Enhancing self-care in diabetes management using self-regulatory processes

Findings from recent research on the self-regulatory process in Type II diabetes mellitus have clinical relevance for nurses and other diabetes educators. We analyzed a symptom self-regulation model and its relationship to demographic and therapeutic variables in persons with Type II diabetes mellitus. The model suggested that when such diabetic clients experienced disease-related symptoms, they used these symptoms as signals of abnormal blood glucose and took action to relieve these symptoms and improve their blood-glucose level. These actions were often judged by the investigators to have no immediate effect on blood-glucose level or, in some cases, to potentially worsen blood glucose. In this article, intervention strategies for nurses and other professionals engaged in diabetic education are developed to improve objective validation of symptom accuracy and to modify some perceptions held by the client with noninsulin-dependent diabetes and, in particular, those clients using oral agents.

Sulphonylurea antidiabetic drugs. An update of their clinical pharmacology and rational therapeutic use

Apart from the amelioration of symptoms, a major aim of the treatment of non-insulin-dependent diabetes mellitus (NIDDM, type 2 diabetes) should be the prevention of cardiovascular complications. These are associated with the chronic hyperglycaemia that is characteristic of NIDDM, and the risk of complications is already increased in subjects with impaired glucose tolerance (IGT). For these reasons, and because hyperglycaemia appears to be a self-perpetuating condition, treatment should be introduced as early as possible and should be aimed at normalisation of blood glucose. To enable early detection and intervention, screening is necessary. As diet regulation alone rarely suffices to normalise blood glucose, addition of sulphonylurea drugs is indicated in many cases. If introduced in the IGT phase, sulphonylureas drugs combined with diet regulation may postpone the development of IGT to manifest NIDDM, and may reduce the increased risk of cardiovascular morbidity and mortality. Sulphonylureas stimulate insulin release, possibly via interaction with receptors in the pancreatic B cells. In addition, such treatment enhances the reduced insulin action. This might be a primary effect but is also a consequence of the increased access to insulin and the subsequent reduction of hyperglycaemia. Sulphonylureas may enhance insulin availability by reducing insulin clearance. Effects on blood lipids are probably secondary phenomena. Fast and short acting sulphonylureas may improve the impaired meal-induced acute insulin release. If combined with weight-reducing diet regulation and introduced early, such treatment can maintain (near) normal blood glucose levels and an improved insulin action for several years without increasing basal insulin secretion, without chronic hyperinsulinaemia, and without weight increase. If not combined with diet regulation, sulphonylurea therapy is likely to fail. If introduced when NIDDM is advanced, the efficacy of these drugs is limited, with secondary failures developing at a rate of 5 to 10% per year. Continuous (24-hour-a-day) exposure to drug treatment could possibly desensitise the B cell to sulphonylurea stimulation. 'Second-generation' sulphonylurea drugs have a higher potency than 'first-generation' drugs, but this need not signify a greater clinical efficacy. The effect of several of these drugs may be increased if they are ingested half an hour before meal(s). Short acting sulphonylureas may be safer than long acting ones, which seem more likely to cause long lasting and fatal hypoglycaemia, at least in elderly patients.(ABSTRACT TRUNCATED AT 400 WORDS)

Management of noninsulin-dependent diabetes mellitus

Management of the patient with NIDDM requires the skill and patience of the physician and the input of a health team, including the dietitian and nurse educator. With perseverance and careful follow up, most treatment goals can be achieved in these patients. The attitude of neglect and easy treatment goals that previously characterized the care of these patients are not justified.