Newer therapeutic options for children with diabetes mellitus: theoretical and practical considerations

Evolving Pharmacotherapeutic Strategies for Type 1 Diabetes Mellitus

Despite pharmacotherapeutic advancements in the management of type 1 diabetes mellitus during the past several decades, patients struggle to achieve glycemic goals. Additionally, hypoglycemia, especially in extremes of age, decreases quality of life. The lack of optimal glycemic control and risk for hypoglycemia are multifactorial. Nevertheless, endeavors aiming to develop pharmacotherapeutic options with enhanced pharmacokinetic, pharmacodynamic, and clinical profiles continue. This review article discusses recent ventures in 3 categories of insulin, non-insulin, and glucagon products.

Use of Sitagliptin With Closed-Loop Technology to Decrease Postprandial Blood Glucose in Type 1 Diabetes

BACKGROUND

Postprandial hyperglycemia poses a challenge to closed-loop systems. Dipeptidyl peptidase-4 (DPP-4) inhibitors, like sitagliptin, reduce postprandial glucose concentrations in patients with type 2 diabetes. The objective of this study was to assess sitagliptin's role in type 1 diabetes (T1DM) as an adjunct therapy in reducing postprandial blood glucose with an insulin-only closed-loop system.

METHODS

This was a randomized, double-blinded, placebo controlled, crossover design trial. The participants were18-35 years old, had T1DM, and an HbA1c of ≤ 8.5%. A dose determination study included eight subjects with T1DM. There were three study visits. Four hours after receiving study drug (placebo, sitagliptin 50 mg, sitagliptin 100 mg), subjects underwent a mixed meal tolerance test with assessment of hormone concentrations. In a second study, 15 subjects underwent two visits receiving either placebo or 100 mg of sitagliptin plus an insulin only closed-loop system for 25 hours with timed meals. Blood glucose and other hormone concentrations were analyzed using repeated measures ANOVA.

RESULTS

For the dose determination study, sitagliptin 100 mg resulted in reduced postprandial blood glucose ( P = .006). For the closed-loop study, glucose concentrations were lower in the treatment group, most prominently during the first two study meals ( P = .03). There was no difference in glucagon concentrations, but insulin concentrations and insulin delivery were lower in the treatment group.

CONCLUSIONS

Sitagliptin may be considered as an adjunct therapy in a closed-loop setting. Larger studies are needed to determine the role of oral agents like sitagliptin to lower postprandial hyperglycemia with closed loop.

Insulin resistance, role of metformin and other non-insulin therapies in pediatric type 1 diabetes

Type 1 diabetes mellitus (T1DM) in youth is a challenging chronic medical condition. Its management should address not only the glycemic control but also insulin resistance and cardiovascular disease risk factors which are increasingly recognized to be present in youth with TID. Current knowledge on the mechanisms of insulin resistance in T1DM is reviewed. The use of adjunctive therapies that are beneficial to achieve adequate glycemic control while mitigating the effects of insulin resistance are discussed with a focus on metformin therapy and an overview of other new pharmacologic agents.

Role of VMH ketone bodies in adjusting caloric intake to increased dietary fat content in DIO and DR rats

The objective of this study was to determine the potential role of astrocyte-derived ketone bodies in regulating the early changes in caloric intake of diet induced-obese (DIO) versus diet-resistant (DR) rats fed a 31.5% fat high-energy (HE) diet. After 3 days on chow or HE diet, DR and DIO rats were assessed for their ventromedial hypothalamic (VMH) ketone bodies levels and neuronal ventromedial hypothalamic nucleus (VMN) sensing using microdialysis coupled to continuous food intake monitoring and calcium imaging in dissociated neurons, respectively. DIO rats ate more than DR rats over 3 days of HE diet intake. On day 3 of HE diet intake, DR rats reduced their caloric intake while DIO rats remained hyperphagic. Local VMH astrocyte ketone bodies production was similar between DR and DIO rats during the first 6 h after dark onset feeding but inhibiting VMH ketone body production in DR rats on day 3 transiently returned their intake of HE diet to the level of DIO rats consuming HE diet. In addition, dissociated VMN neurons from DIO and DR rats were equally sensitive to the largely excitatory effects of β-hydroxybutyrate. Thus while DR rats respond to increased VMH ketone levels by decreasing their intake after 3 days of HE diet, this is not the case of DIO rats. These data suggest that DIO inherent leptin resistance prevents ketone bodies inhibitory action on food intake.

Role of FAT/CD36 in fatty acid sensing, energy, and glucose homeostasis regulation in DIO and DR rats

Hypothalamic fatty acid (FA) sensing neurons alter their activity utilizing the FA translocator/receptor, FAT/CD36. Depletion of ventromedial hypothalamus (VMH) CD36 with adeno-associated viral vector expressing CD36 shRNA (AAV CD36 shRNA) leads to redistribution of adipose stores and insulin resistance in outbred rats. This study assessed the requirement of VMH CD36-mediated FA sensing for the regulation of energy and glucose homeostasis in postnatal day 5 (P5) and P21 selectively bred diet-induced obese (DIO) and diet-resistant (DR) rats using VMH AAV CD36 shRNA injections. P5 CD36 depletion altered VMH neuronal FA sensing predominantly in DIO rats. After 10 wk on a 45% fat diet, DIO rats injected with VMH AAV CD36 shRNA at P21 ate more and gained more weight than DIO AAV controls, while DR AAV CD36 shRNA-injected rats gained less weight than DR AAV controls. VMH CD36 depletion increased inguinal fat pad weights and leptin levels in DIO and DR rats. Although DR AAV CD36 shRNA-injected rats became as obese as DIO AAV controls, only DIO control and CD36 depleted rats became insulin-resistant on a 45% fat diet. VMH CD36 depletion stunted linear growth in DIO and DR rats. DIO rats injected with AAV CD36 shRNA at P5 had increased fat mass, mostly due to a 45% increase in subcutaneous fat. They were also insulin-resistant with an associated 71% increase of liver triglycerides. These results demonstrate that VMH CD36-mediated FA sensing is a critical factor in the regulation of energy and glucose homeostasis and fat deposition in DIO and DR rats.

Incretins and amylin in pediatric diabetes: new tools for management of diabetes in youth

PURPOSE OF REVIEW

The purpose of this review is to examine recently published literature in the areas of incretins and amylin in the management of pediatric diabetes.

RECENT FINDINGS

Recent studies have begun to explore the use of longer-acting GLP-1 analogues that can be given once daily, such as liraglutide, and the use of DPP-IV inhibitors in the management of type 2 diabetes. In addition, recent studies have been published on the use of exenatide in the management of pediatric obesity and newly diagnosed type 1 diabetes.

SUMMARY

Very few medications are approved for management of type 2 diabetes in youth. In addition, monotherapy of type 1 diabetes in youth with insulin does not achieve HbA1c targets in the majority of youth despite the use of rapid-acting insulin analogues, insulin pump therapy, and continuous glucose monitoring. Novel therapies that target physiologic modalities other than enhancing or replacing insulin secretion or improving insulin sensitivity have shown efficacy in adults. Studies with these drugs are being done in the pediatric population and should provide additional treatment options for these patients.

Point of care testing for pediatric following up of hemoglobin A1C: Concern on product's property

Point of care testing (POCT) is a new concept in laboratory medicine. The POCT tool helps perform the laboratory test at site giving fast result and requires only small amount of sample. It is presently and increasingly used in pediatrics. In pediatric diabetology, the use of POCT for following up of hemoglobin A1C is a new concept. At present, there are several POCT tools for this purpose. In this specific article, the author compares on important aspects (turnaround time and required amount of specimen) of 5 available POCT tools for measurement of hemoglobin A1C level. The test that is the fastest and requires the least amount of blood sample, which means the least harm to the pediatric patient is the most preferable. Here, it can be seen that there is no ideal POCT that has both properties. However, if it is standardized to compare the amount of required blood sample, the special concern in the pediatric patients, the product from multiplication shows that Siemen DCA 2000+ and Siemen DCA Vantage are the two most preferable POCT tools for hemoglobin A1C determination in pediatric diabetes mellitus management.

The use of exenatide in severely burned pediatric patients

Introduction

Intensive insulin treatment (IIT) has been shown to improve outcomes post-burn in severely burnt patients. However, it increases the incidence of hypoglycemia and is associated with risks and complications. We hypothesized that exenatide would decrease plasma glucose levels post-burn to levels similar to those achieved with IIT, and reduce the amount of exogenous insulin administered.

Methods

This open-label study included 24 severely burned pediatric patients. Six were randomized to receive exenatide, and 18 received IIT during acute hospitalization (block randomization). Exenatide and insulin were administered to maintain glucose levels between 80 and 140 mg/dl. We determined 6 AM, daily average, maximum and minimum glucose levels. Variability was determined using mean amplitude of glucose excursions (MAGE) and percentage of coefficient of variability. The amount of administered insulin was compared in both groups.

Results

Glucose values and variability were similar in both groups: Daily average was 130 ± 28 mg/dl in the intervention group and 138 ± 25 mg/dl in the control group (P = 0.31), MAGE 41 ± 6 vs. 45 ± 12 (respectively). However, administered insulin was significantly lower in the exenatide group than in the IIT group: 22 ± 14 IU patients/day in the intervention group and 76 ± 11 IU patients/day in the control group (P = 0.01). The incidence rate of hypoglycemia was similar in both groups (0.38 events/patient-month).

Conclusions

Patients receiving exenatide received significantly lower amounts of exogenous insulin to control plasma glucose levels. Exenatide was well tolerated and potentially represents a novel agent to attenuate hyperglycemia in the critical care setting.

Trial registration

NCT00673309.

Reducing postprandial hyperglycemia with adjuvant premeal pramlintide and postmeal insulin in children with type 1 diabetes mellitus

OBJECTIVE

The purpose of this study was to determine the effect of adjuvant premeal pramlintide with postmeal insulin on postprandial hyperglycemia in children with type 1 diabetes mellitus (T1DM).

METHODS

Eight adolescents with T1DM on intensive insulin therapy participated in an open-label, non-randomized, crossover study, comparing postprandial glucose excursions in study A (prescribed insulin regimen and given premeal) vs. study B (pramlintide + insulin). Prandial insulin dose for study B was decreased by 20% and given postmeal, while pramlintide was given just before the meal. Blood glucose (BG), glucagon, and pramlintide concentrations were measured basally and at timed intervals during a 300-min study period.

RESULTS

Postprandial incremental BG for the duration of the study was reduced in study B vs. study A with AUC((-60 to 300 min)) (area under the curve) at 6600 +/- 2371 vs. 20 230 +/- 3126 mg/dL/min (367 +/- 132 vs. 1124 +/- 174 mmol/L/min) (p < 0.001). Glucagon concentration was suppressed for approximately 120 min following administration of 30 microg of pramlintide and postmeal insulin (p < 0.003). No severe hypoglycemic episodes were experienced in this study.

CONCLUSIONS

Postprandial hyperglycemia is considerably reduced in adolescents with T1DM when treated with fixed-dose premeal pramlintide, and precisely calculated postmeal insulin, without significant side effects.

New potential adjuncts to treatment of children with type 1 diabetes mellitus

Insulin administration is the primary therapy for type 1 diabetes mellitus (T1DM). Current available insulin therapies do not successfully enable children with T1DM to reach glycemic goals without side effects such as hypoglycemia and weight gain. Pramlintide is a synthetic analog of human amylin that acts in conjunction with insulin to delay gastric emptying and inhibit the release of glucagon and is indicated for use in patients with type 1 and type 2 diabetes. Recent studies in adult patients have examined the role of glucagon-like peptide 1 (GLP-1) and agents that bind to its receptor in type 1 diabetes. It is hypothesized that a major component of the glycemic effect is attributable to the known action of GLP-1 to delay gastric emptying and to inhibit glucagon secretion. Further studies with the use of amylin analogs and long-acting GLP-1 agonists as congeners with insulin in T1DM are indicated in children. In recent years, our better understanding of the pathophysiology of diabetes has led to the development of new therapies for diabetes. This article reviews the potential use of these newer pharmacologic agents as adjunctive therapy in T1DM in children and adolescents.

[Adjunctive therapies to glycaemic control of type 1 diabetes mellitus]

Since Diabetes Control and Complications Trial (DCCT), intensive therapy has been directed at achieving glucose and glycosylated hemoglobin (HbA1c) values as close to normal as possible regarding safety issues. However, hyperglycemia (especially postprandial hyperglycemia) and hypoglicemia continue to be problematic in the management of type 1 diabetes. The objective of associating other drugs to insulin therapy is to achieve better metabolic control lowering postprandial blood glucose levels. Adjunctive therapies can be divided in four categories based on their mechanism of action: enhancement of insulin action (e.g. the biguanides and thiazolidinediones), alteration of gastrointestinal nutrient delivery (e.g. acarbose and amylin) and other targets of action (e.g. pirenzepine, insulin-like growth factor I and glucagon-like peptide-1). Many of these agents have been found to be effective in short-term studies with decreases in HbA1c of 0.5-1%, lowering postprandial blood glucose levels and decreasing daily insulin doses.

High yield production of recombinant native and modified peptides exemplified by ligands for G-protein coupled receptors

G-protein coupled receptors (GPCRs) comprise a large family of membrane proteins and attract pharmaceutical interest as therapeutic targets. Two examples of class B GPCRs that are involved in metabolic diseases are the Parathyroid hormone receptor 1 (PTHR1) and the Glucagon-like-peptide-1 receptor (GLP-1R) which play central roles in osteoporosis and diabetes mellitus type II, respectively. Class B GPCRs are characterised by a large extracellular N-terminal domain with a typical disulfide bridge pattern. This domain is responsible for the binding of peptide hormone ligands. Here we report the recombinant expression of these ligands in natural and several modified forms for their use in functional assays, NMR analyses or affinity purification of receptor/ligand complexes for crystallisation. Applying the SUMO system, low cost expression of soluble fusion-proteins is achieved. Moreover, via the SUMO cleavage site, the authentic N-terminal sequence which is essential for ligand-receptor interactions can be obtained. Purification of the peptide by RP-HPLC results in >98% pure preparations. The strategy can also be adopted for many other purposes, especially if small peptides are needed at either large amounts or with specific features like isotope, affinity or fluorescent labels. Furthermore, for the growing demand for therapeutic peptides, this method could represent a straightforward production process.