Renal glucose metabolism in normal physiological conditions and in diabetes.

The kidney plays an important role in glucose homeostasis via gluconeogenesis, glucose utilization, and glucose reabsorption from the renal glomerular filtrate. After an overnight fast, 20-25% of glucose released into the circulation originates from the kidneys through gluconeogenesis. In this post-absorptive state, the kidneys utilize about 10% of all glucose utilized by the body. After glucose ingestion, renal gluconeogenesis increases and accounts for approximately 60% of endogenous glucose release in the postprandial period. Each day, the kidneys filter approximately 180g of glucose and virtually all of this is reabsorbed into the circulation. Hormones (most importantly insulin and catecholamines), substrates, enzymes, and glucose transporters are some of the various factors influencing the kidney's role. Patients with type 2 diabetes have an increased renal glucose uptake and release in the fasting and the post-prandial states. Additionally, glucosuria in these patients does not occur at plasma glucose levels that would normally produce glucosuria in healthy individuals. The major abnormality of renal glucose metabolism in type 1 diabetes appears to be impaired renal glucose release during hypoglycemia.

Hypoglycemia in Patients with Diabetes and Renal Disease.

This article summarizes our current knowledge of the epidemiology, pathogenesis, and morbidity of hypoglycemia in patients with diabetic kidney disease and reviews therapeutic limitations in this situation.

Efficacy and safety of lixisenatide in elderly (≥65 years old) and very elderly (≥75 years old) patients with type 2 diabetes: an analysis from the GetGoal phase III programme.

BACKGROUND: The objective of this article is to evaluate the pharmacokinetics, efficacy and safety of lixisenatide (subcutaneous injection) in elderly (≥65 years old) and very elderly (≥75 years old) patients with type 2 diabetes mellitus. METHODS: We conducted a phase I, single-centre, open-label study to evaluate the safety and pharmacokinetics of a single lixisenatide 20 µg dose and a pooled analysis of six randomized, placebo-controlled, phase III studies (12-month or 24-month duration) that evaluated glycaemic parameters and safety in patients receiving lixisenatide 20 µg once daily or placebo. RESULTS: The pharmacokinetics study included 36 healthy subjects, including 18 elderly healthy subjects (≥65 years old) and 18 matched young healthy subjects (18-45 years old). The pooled analysis included 3188 patients, including 2565 patients <65 years old and 623 patients ≥65 years old (including 79 patients ≥75 years old). Mean exposure with lixisenatide 20 µg was ~30% higher in elderly than in young subjects, and the terminal half-life was prolonged by ~1.6 times. Maximum concentration (C(max)) and time to C(max) (t(max)) were comparable in both groups. Equal numbers of elderly and young subjects reported treatment-emergent adverse events, the majority of which were gastrointestinal disorders. In the pooled analysis, lixisenatide 20 µg once daily provided significant reductions in HbA1c versus placebo for all age groups. There was a similar incidence of treatment-emergent adverse events across all age groups (range: 69-73%). The incidence of symptomatic hypoglycaemia was generally comparable between lixisenatide-treated and placebo-treated patients. CONCLUSION: These data suggest that lixisenatide is effective and well tolerated in elderly and very elderly patients with type 2 diabetes mellitus.

Hypoglycemia, chronic kidney disease, and diabetes mellitus.

Hypoglycemia is a major problem associated with substantial morbidity and mortality in patients with diabetes and is often a major barrier to achieving optimal glycemic control. Chronic kidney disease not only is an independent risk factor for hypoglycemia but also augments the risk of hypoglycemia that is already present in people with diabetes. This article summarizes our current knowledge of the epidemiology, pathogenesis, and morbidity of hypoglycemia in patients with diabetes and chronic kidney disease and reviews therapeutic considerations in this situation. PubMed and MEDLINE were searched for literature published in English from January 1989 to May 2014 for diabetes mellitus, hypoglycemia, chronic kidney disease, and chronic renal insufficiency.

SGLT2 inhibitors in the treatment of type 2 diabetes.

The kidney plays an important role in glucose homeostasis via its production, utilization, and, most importantly, reabsorption of glucose from glomerular filtrate which is largely mediated via the sodium glucose co-transporter 2 (SGLT2). Pharmacological inhibition of SGLT2 increases urinary glucose excretion and decreases plasma glucose levels in an insulin-independent manner. Agents that inhibit SGLT2 represent a novel class of drugs, which has recently become available for treatment of type 2 diabetes. This article summarizes the rationale for use of these agents and reviews available clinical data on their efficacy, safety, and risks/benefits.

Hypoglycemia.

Hypoglycemia remains a common problem for patients with diabetes and is associated with substantial morbidity and mortality. This article summarizes our current knowledge of the epidemiology, pathogenesis, risk factors, and complications of hypoglycemia in patients with diabetes and discusses prevention and treatment strategies.

Efficacy and safety of lixisenatide once daily versus exenatide twice daily in type 2 diabetes inadequately controlled on metformin: a 24-week, randomized, open-label, active-controlled study (GetGoal-X).

OBJECTIVE: To compare efficacy and safety of lixisenatide once daily versus exenatide twice daily in type 2 diabetes inadequately controlled with metformin. RESEARCH DESIGN AND METHODS: Adults with diabetes inadequately controlled (HbA1c 7-10%) with metformin were randomized to lixisenatide 20 µg once daily (n=318) or exenatide 10 µg twice daily (n=316) in a 24-week (main period), open-label, parallel-group, multicenter study. The primary objective was a noninferiority assessment of lixisenatide versus exenatide in HbA1c change from baseline to week 24. RESULTS: Lixisenatide once daily demonstrated noninferiority in HbA1c reduction versus exenatide twice daily. The least squares mean change was -0.79% (mean decrease 7.97 to 7.17%) for lixisenatide versus -0.96% (mean decrease 7.96 to 7.01%) for exenatide, and treatment difference was 0.17% (95% CI, 0.033-0.297), meeting a predefined noninferiority upper CI margin of 0.4%. Responder rate (HbA1c<7.0%) and improvements in fasting plasma glucose were comparable. Both agents induced weight loss (from 94.5 to 91.7 kg and from 96.7 to 92.9 kg with lixisenatide and exenatide, respectively). Incidence of adverse events (AEs) was similar for lixisenatide and exenatide, as was incidence of serious AEs (2.8 and 2.2%, respectively). Discontinuations attributable to AEs occurred in 33 lixisenatide (10.4%) and 41 exenatide (13.0%) patients. In the lixisenatide group, fewer participants experienced symptomatic hypoglycemia (2.5 vs. 7.9%; P<0.05), with fewer gastrointestinal events (especially nausea; 24.5 vs. 35.1%; P<0.05). CONCLUSIONS: Add-on lixisenatide once daily in type 2 diabetes inadequately controlled with metformin demonstrated noninferior improvements in HbA1c, with slightly lower mean weight loss, lower incidence of hypoglycemia, and better gastrointestinal tolerability compared with exenatide twice daily.

Pathogenesis and management of postprandial hyperglycemia: role of incretin-based therapies.

Postprandial plasma glucose concentrations are an important contributor to glycemic control. There is evidence suggesting that postprandial hyperglycemia may be an independent risk factor for cardiovascular disease. Glucagon-like peptide-1 (GLP-1) receptor agonists and dipeptidyl peptidase-4 (DPP-4) inhibitors are antidiabetic agents that predominantly reduce postprandial plasma glucose levels. DPP-4 inhibitors are associated with fewer gastrointestinal side effects than GLP-1 receptor agonists and are administered orally, unlike GLP-1 analogs, which are administered as subcutaneous injections. GLP-1 receptor agonists are somewhat more effective than DPP-4 inhibitors in reducing postprandial plasma glucose and are usually associated with significant weight loss. For these reasons, GLP-1 receptor agonists are generally preferred over DPP-4 inhibitors as part of combination treatment regimens in patients with glycated hemoglobin levels above 8.0%. This article reviews the pathogenesis of postprandial hyperglycemia, the mechanisms by which GLP-1 receptor agonists and DPP-4 inhibitors reduce postprandial plasma glucose concentrations, and the results of recent clinical trials (ie, published 2008 to October 2012) that evaluated the effects of these agents on postprandial plasma glucose levels when evaluated as monotherapy compared with placebo or as add-on therapy to metformin, a sulfonylurea, or insulin. Findings from recent clinical studies suggest that both GLP-1 receptor agonists and DPP-4 inhibitors could become valuable treatment options for optimizing glycemic control in patients unable to achieve glycated hemoglobin goals on basal insulin, with the added benefits of weight loss and a low risk of hypoglycemia.

Efficacy and safety of the once-daily GLP-1 receptor agonist lixisenatide in monotherapy: a randomized, double-blind, placebo-controlled trial in patients with type 2 diabetes (GetGoal-Mono).

OBJECTIVE: To assess efficacy and safety of lixisenatide monotherapy in type 2 diabetes. RESEARCH DESIGN AND METHODS: Randomized, double-blind, 12-week study of 361 patients not on glucose-lowering therapy (HbA(1c) 7-10%) allocated to one of four once-daily subcutaneous dose increase regimens: lixisenatide 2-step (10 µg for 1 week, 15 µg for 1 week, and then 20 µg; n = 120), lixisenatide 1-step (10 µg for 2 weeks and then 20 µg; n = 119), placebo 2-step (n = 61), or placebo 1-step (n = 61) (placebo groups were combined for analyses). Primary end point was HbA(1c) change from baseline to week 12. RESULTS: Once-daily lixisenatide significantly improved HbA(1c) (mean baseline 8.0%) in both groups (least squares mean change vs. placebo: -0.54% for 2-step, -0.66% for 1-step; P < 0.0001). Significantly more lixisenatide patients achieved HbA(1c) <7.0% (52.2% 2-step, 46.5% 1-step) and ≤ 6.5% (31.9% 2-step, 25.4% 1-step) versus placebo (26.8% and 12.5%, respectively; P < 0.01). Lixisenatide led to marked significant improvements of 2-h postprandial glucose levels and blood glucose excursions measured during a standardized breakfast test. A significant decrease in fasting plasma glucose was observed in both lixisenatide groups versus placebo. Mean decreases in body weight (∼2 kg) were observed in all groups. The most common adverse events were gastrointestinal-nausea was the most frequent (lixisenatide 23% overall, placebo 4.1%). Symptomatic hypoglycemia occurred in 1.7% of lixisenatide and 1.6% of placebo patients, with no severe episodes. Safety/tolerability was similar for the two dose regimens. CONCLUSIONS: Once-daily lixisenatide monotherapy significantly improved glycemic control with a pronounced postprandial effect (75% reduction in glucose excursion) and was safe and well tolerated in type 2 diabetes.

Development of the sodium-glucose co-transporter 2 inhibitor dapagliflozin for the treatment of patients with type 2 diabetes mellitus.

Dapagliflozin is a highly selective sodium-glucose co-transporter 2 inhibitor developed for the treatment of Type 2 diabetes mellitus. Its inhibition of sodium-glucose co-transporter 2 blocks glucose reabsorption in the proximal tubule of the kidney, increasing renal glucose excretion via the urine, resulting in reduction of glycated hemoglobin, fasting plasma glucose and postprandial plasma glucose in patients with Type 2 diabetes mellitus. The pharmacokinetics and pharmacodynamics of dapagliflozin are suitable for once-daily dosing. Dapagliflozin improves glycemic control when used as monotherapy and when used in combination with other antidiabetic treatments. Throughout all phases of clinical studies, dapagliflozin was generally well tolerated. Increased events suggestive of urinary tract and genital infections have been reported; most resolved with conventional treatment. Unexpected numerical imbalances between dapagliflozin and comparator were noted for breast and bladder cancers. The potential for increased cancer risk with dapagliflozin needs to be further assessed.

DPP-4 inhibitors: what may be the clinical differentiators?

Attenuation of the prandial incretin effect, mediated by glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic peptide (GIP), contributes to hyperglycemia in type 2 diabetes mellitus (T2DM). Since the launch of sitagliptin in 2006, a compelling body of evidence has accumulated showing that dipeptidyl peptidase-4 (DPP-4) inhibitors, which augment endogenous GLP-1 and GIP levels, represent an important advance in the management of T2DM. Currently, three DPP-4 inhibitors - sitagliptin, vildagliptin and saxagliptin - have been approved in various countries worldwide. Several other DPP-4 inhibitors, including linagliptin and alogliptin, are currently in clinical development. As understanding of, and experience with, the growing number of DPP-4 inhibitors broadens, increasing evidence suggests that the class may offer advantages over other antidiabetic drugs in particular patient populations. The expanding evidence base also suggests that certain differences between DPP-4 inhibitors may prove to be clinically significant. This therapeutic diversity should help clinicians tailor treatment to the individual patient, thereby increasing the proportion that safely attain target HbA(1c) levels, and reducing morbidity and mortality. This review offers an overview of DPP-4 inhibitors in T2DM and suggests some characteristics that may provide clinically relevant differentiators within this class.

Type 2 diabetes: postprandial hyperglycemia and increased cardiovascular risk.

Hyperglycemia is a major risk factor for both the microvascular and macrovascular complications in patients with type 2 diabetes. This review summarizes the cardiovascular results of large outcomes trials in diabetes and presents new evidence on the role of hyperglycemia, with particular emphasis on postprandial hyperglycemia, in adverse cardiovascular outcomes in patients with type 2 diabetes. Treatment options, including the new dipeptidyl peptidase-4 inhibitors and glucagon-like peptide-1 mimetics that primarily target postprandial hyperglycemia, are also discussed. Hyperglycemia increases cardiovascular mortality, and reducing hyperglycemia lowers cardiovascular risk parameters. Control of both fasting and postprandial hyperglycemia is necessary to achieve optimal glycated hemoglobin control. Therefore, anti-hyperglycemic agents that preferentially target postprandial hyperglycemia, along with those that preferentially target fasting hyperglycemia, are strongly suggested to optimize individual diabetes treatment strategies and reduce complications.

Diabetes mellitus and gastric emptying: questions and issues in clinical practice.

It is long known that both type 1 and type 2 diabetes can be associated with changes in gastric emptying; a number of publications have linked diabetes to delayed gastric emptying of variable severity and often with poor relationship to gastrointestinal symptomatology. In contrast, more recent studies have reported accelerated gastric emptying when adjusted for glucose concentration in patients with diabetes, indicating a reciprocal relationship between gastric emptying and ambient glucose concentrations. This review proposes that gastroparesis or gastroparesis diabeticorum, a severe condition characterized by a significant impairment of gastric emptying accompanied by severe nausea, vomiting, and malnutrition, is often overdiagnosed and not well contrasted with delays in gastric emptying. The article offers a clinically relevant definition of gastroparesis that should help differentiate this rare condition from (often asymptomatic) delays in gastric emptying. The fact that delayed gastric emptying can also be observed in non-diabetic individuals under experimental conditions in which hyperglycaemia is artificially induced suggests that a delay in gastric emptying rate when blood glucose concentrations are high is actually an appropriate physiological response to hyperglycaemia, slowing further increases in blood glucose. The article discusses the strengths and weaknesses of various methodologies for assessing gastric emptying, especially with respect to the diabetes population, and reviews newer diabetes therapies that decelerate the rate of gastric emptying. These therapies may be a beneficial tool in managing postprandial hyperglycaemia because they attenuate rapid surges in glucose concentrations by slowing the delivery of meal-derived glucose.

Different pathophysiology of impaired glucose tolerance in first-degree relatives of individuals with type 2 diabetes mellitus.

To assess whether an increased genetic predisposition for type 2 diabetes mellitus (T2DM) influences the contributions of insulin resistance and impaired insulin secretion to impaired glucose tolerance (IGT), 437 subjects not known to have T2DM underwent an oral glucose tolerance test and a 3-hour hyperglycemic clamp. Plasma insulin responses and insulin sensitivity were compared between all subjects (unselected for demographic or anthropometric characteristics) who had normal glucose homeostasis and no first-degree T2DM relative (n = 133), IGT with a first-degree T2DM relative (IGT/FH+, n = 74), or IGT without a first-degree T2DM relative (IGT/FH-, n = 50). Compared with those with normal glucose homeostasis, first- and second-phase plasma insulin responses were reduced approximately 45% and 30%, respectively (both P < .001), in IGT/FH+, whereas insulin sensitivity was only approximately 20% reduced (P = .011). In contrast, in IGT/FH-, first-phase plasma insulin responses were only approximately 20% reduced (P = .016), second-phase plasma insulin responses were not reduced, but insulin sensitivity was approximately 40% reduced (P < .001). The IGT/FH+ group differed significantly from the IGT/FH- group by having 25% to 30% lower first-phase plasma insulin responses (P = .026) and 25% to 30% greater insulin sensitivity (P = .027). Adjustment for obesity abolished the differences in insulin resistance but not plasma insulin responses. However, when the IGT groups were stratified into subgroups based on body mass index (BMI), first-phase plasma insulin responses were approximately 30% lower in IGT/FH+ with a BMI of at least 27 kg/m(2) (P = .018) but similar in IGT/FH+ with a BMI less than 27 kg/m(2) compared with the corresponding IGT/FH- subgroups. We conclude that, in IGT, an increased genetic predisposition for T2DM increases the contribution of impaired insulin secretion to its pathophysiology. This effect is enhanced by obesity.

Efficacy and safety of the human glucagon-like peptide-1 analog liraglutide in combination with metformin and thiazolidinedione in patients with type 2 diabetes (LEAD-4 Met+TZD).

OBJECTIVE: To determine the efficacy and safety of liraglutide (a glucagon-like peptide-1 receptor agonist) when added to metformin and rosiglitazone in type 2 diabetes. RESEARCH DESIGN AND METHODS: This 26-week, double-blind, placebo-controlled, parallel-group trial randomized 533 subjects (1:1:1) to once-daily liraglutide (1.2 or 1.8 mg) or liraglutide placebo in combination with metformin (1 g twice daily) and rosiglitazone (4 mg twice daily). Subjects had type 2 diabetes, A1C 7-11% (previous oral antidiabetes drug [OAD] monotherapy >or=3 months) or 7-10% (previous OAD combination therapy >or=3 months), and BMI

Is a history of gestational diabetes related to risk factors for coronary heart disease?

Coronary heart disease (CHD) risk in 20 non-diabetic women with and 20 without a distant history of gestational diabetes (hGDM), matched on age, body mass index, and time since GDM-affected pregnancy, was compared in a case control study. Women with an hGDM had lower high-density lipoprotein cholesterol (HDL-c), p = .02, and higher triglycerides, p < or = .001, versus controls. The combination of high triglycerides and low HDL-c occurred in 25% of hGDM cases versus 0% of controls, p

Impaired hyperglycemia-induced delay in gastric emptying in patients with type 1 diabetes deficient for islet amyloid polypeptide.

OBJECTIVE: Slowing of gastric emptying by hyperglycemia, a physiological response to minimize postprandial hyperglycemia, may be impaired in patients with type 1 diabetes. The causes and consequences on glucose homeostasis are unknown. RESEARCH DESIGN AND METHODS: Consequences of euglycemia- and hyperglycemia-induced changes in gastric emptying on postprandial glucose fluxes and excursions were studied in 10 healthy subjects and 15 type 1 diabetic subjects after ingestion of a mixed meal using the double isotope approach ([6,6-(2)H(2)] and [1-(13)C]glucose) and scintigraphic measurements of gastric emptying. RESULTS: Gastric emptying was greater in type 1 diabetic subjects (90-120 min, P < 0.03), and 50% retention times were comparable in healthy subjects and type 1 diabetic subjects (167 +/- 8 vs. 152 +/- 10, P = 0.32). Hyperglycemia markedly delayed gastric emptying in healthy subjects but did not alter it in type 1 diabetic subjects (50% retention time 222 +/- 18 vs. 167 +/- 8 min, P = 0.003 and 148 +/- 9 vs. 152 +/- 10 min, P = 0.51). Plasma islet amyloid polypeptide (IAPP) increased approximately fourfold in healthy subjects (P < 0.001), whereas it was undetectable in type 1 diabetic subjects. IAPP replacement, using the analog pramlintide, in type 1 diabetic subjects slowed gastric emptying to a comparable extent, as did hyperglycemia in healthy subjects (P < 0.14), and greatly reduced postprandial hyperglycemia (P < 00.1). Meal-derived glucose appearance in plasma (10.7 +/- 0.5 vs. 6.8 +/- 0.7 mumol . kg(-1) . min(-1), P < 0.001) was reduced, and splanchnic glucose sequestration increased (14.0 +/- 3.0 vs. 25.0 +/- 6.0%, P = 0.04). CONCLUSIONS: In patients with type 1 diabetes the ability to delay gastric emptying in response to hyperglycemia is impaired. This impairment contributes to exaggerated rates of meal-derived glucose appearance and, ultimately, postprandial glucose excursions.

Guideline for management of postmeal glucose.

An estimated 246 million people worldwide have diabetes. Diabetes is a leading cause of death in most developed countries, and is reaching epidemic proportions in many developing and newly industrialized nations. Poorly controlled diabetes is associated with the development of renal failure, vision loss, macrovascular diseases and amputations. Large controlled clinical trials have demonstrated that intensive treatment of diabetes can significantly decrease the development and/or progression of microvascular complications of diabetes. There appears to be no glycaemic threshold for reduction of diabetes complications; the lower the glycated haemoglobin (HbA1c), the lower the risk. The progressive relationship between plasma glucose levels and cardiovascular risk extends well below the diabetic threshold. Until recently, the predominant focus of therapy has been on lowering HbA1c levels, with a strong emphasis on fasting plasma glucose. Although control of fasting hyperglycaemia is necessary, it is usually insufficient to obtain optimal glycaemic control. A growing body of evidence suggests that reducing postmeal plasma glucose excursions is as important, or perhaps more important for achieving HbA1c goals. This guideline reviews the evidence on the harmful effects of elevated postmeal glucose and makes recommendations on its treatment, assessment and targets.

Effect of aging on glucose homeostasis: accelerated deterioration of beta-cell function in individuals with impaired glucose tolerance.

OBJECTIVE: To examine the effect of aging on insulin secretion (first- and second-phase insulin release) and insulin sensitivity in people with normal glucose tolerance (NGT) or impaired glucose tolerance (IGT). RESEARCH DESIGN AND METHODS: First- and second-phase insulin secretion and insulin sensitivity were assessed in hyperglycemic clamp experiments in 266 individuals with NGT and 130 individuals with IGT, ranging in age from approximately 20 to approximately 70 years. Changes in beta-cell function were compared using the disposition index to adjust for differences in insulin sensitivity. RESULTS: As expected, both phases of insulin release and insulin sensitivity were reduced in individuals with IGT (all P < 0.01). Insulin sensitivity was not independently correlated with age in either group. In people with NGT, the disposition index for first- and second-phase insulin release decreased similarly at a rate of approximately 0.7% per year. In people with IGT, the disposition indexes for first- and second-phase insulin release decreased at greater rates ( approximately 2.2 and 1.4% per year, P = 0.002 and 0.009, respectively, vs. NGT), with the decrease in first phase being greater than that of second phase (P = 0.025). CONCLUSIONS: Insulin secretion (both first and second phase) normally decreases at a rate of approximately 0.7% per year with aging; this decrease in beta-cell function is accelerated about two-fold in people with impaired glucose tolerance-first phase to a greater extent than second phase. Finally, aging per se has no effect on insulin sensitivity independent of changes in body composition.