Personalized pharmacotherapy for Type 2 diabetes mellitus

An Update on the Molecular and Cellular Basis of Pharmacotherapy in Type 2 Diabetes Mellitus

Diabetes mellitus (DM) is a chronic illness with an increasing global prevalence. More than 537 million cases of diabetes were reported worldwide in 2021, and the number is steadily increasing. The worldwide number of people suffering from DM is projected to reach 783 million in 2045. In 2021 alone, more than USD 966 billion was spent on the management of DM. Reduced physical activity due to urbanization is believed to be the major cause of the increase in the incidence of the disease, as it is associated with higher rates of obesity. Diabetes poses a risk for chronic complications such as nephropathy, angiopathy, neuropathy and retinopathy. Hence, the successful management of blood glucose is the cornerstone of DM therapy. The effective management of the hyperglycemia associated with type 2 diabetes includes physical exercise, diet and therapeutic interventions (insulin, biguanides, second generation sulfonylureas, glucagon-like peptide 1 agonists, dipeptidyl-peptidase 4 inhibitors, thiazolidinediones, amylin mimetics, meglitinides, α-glucosidase inhibitors, sodium-glucose cotransporter-2 inhibitors and bile acid sequestrants). The optimal and timely treatment of DM improves the quality of life and reduces the severe burden of the disease for patients. Genetic testing, examining the roles of different genes involved in the pathogenesis of DM, may also help to achieve optimal DM management in the future by reducing the incidence of DM and by enhancing the use of individualized treatment regimens.

Comparative effects of prolonged and intermittent stimulation of the glucagon-like peptide 1 receptor on gastric emptying and glycemia

Acute administration of glucagon-like peptide 1 (GLP-1) and its agonists slows gastric emptying, which represents the major mechanism underlying their attenuation of postprandial glycemic excursions. However, this effect may diminish during prolonged use. We compared the effects of prolonged and intermittent stimulation of the GLP-1 receptor on gastric emptying and glycemia. Ten healthy men received intravenous saline (placebo) or GLP-1 (0.8 pmol/kg ⋅ min), as a continuous 24-h infusion ("prolonged"), two 4.5-h infusions separated by 20 h ("intermittent"), and a 4.5-h infusion ("acute") in a randomized, double-blind, crossover fashion. Gastric emptying of a radiolabeled mashed potato meal was measured using scintigraphy. Acute GLP-1 markedly slowed gastric emptying. The magnitude of the slowing was attenuated with prolonged but maintained with intermittent infusions. GLP-1 potently diminished postprandial glycemia during acute and intermittent regimens. These observations suggest that short-acting GLP-1 agonists may be superior to long-acting agonists when aiming specifically to reduce postprandial glycemic excursions in the treatment of type 2 diabetes.

The methodology of glucose monitoring in type 2 diabetes mellitus

Type 2 diabetes is a chronic disease and maintaining a tight glycemic control is essential to prevent both microvascular and macrovascular complications, as demonstrated in previous studies. It is essential to monitor the glucose levels in order to achieve the targets. The blood glucose monitoring can be done by different methods: glycated haemoglobin A1c, self-monitoring of blood glucose (before and after meals) with a glucometer and continuous glucose monitoring with a system that measures interstitial glucose concentrations. Even though glycated haemoglobin A1c is considered the "gold standard" of diabetes care, it does not provide complete information about the magnitude of the glycemic disequilibrium. Therefore the self-monitoring and continuous monitoring of blood glucose are considered an important adjunct for achieving and maintaining optimal glycemic control. The three methods of assessing glycemic control: HbA1c, SMBG and CGMS provide distinct but at the same time complementary information.

Individualized therapy for type 2 diabetes: clinical implications of pharmacogenetic data

Type 2 diabetes mellitus (T2DM) is characterized by insulin resistance, abnormally elevated hepatic glucose production, and reduced glucose-stimulated insulin secretion. Treatment with antihyperglycemic agents is initially successful in type 2 diabetes, but it is often associated with a high secondary failure rate, and the addition of insulin is eventually necessary for many patients, in order to restore acceptable glycemic control and to reduce the risk of development and progression of disease complications. Notably, even patients who appear to have similar requirements of antidiabetic regimens show great variability in drug disposition, glycemic response, tolerability, and incidence of adverse effects during treatment. Pharmacogenomics is a promising area of investigation and involves the search for genetic polymorphisms that may explain the interindividual variability in antidiabetic therapy response. The initial positive results portend that genomic efforts will be able to shed important light on variability in pharmacologic traits. In this review, we summarize the current understanding of genetic polymorphisms that may affect the responses of subjects with T2DM to antidiabetic treatment. These genes belong to three major classes: genes involved in drug metabolism and transporters that influence pharmacokinetics (including the cytochrome P450 [CYP] superfamily, the organic anion transporting polypeptide [OATP] family, and the polyspecific organic cation transporter [OCT] family); genes encoding drug targets and receptors (including peroxisome proliferator-activated receptor gamma [PPARG], the adenosine triphosphate [ATP]-sensitive potassium channel [K(ATP)], and incretin receptors); and genes involved in the causal pathway of T2DM that are able to modify the effects of drugs (including adipokines, transcription factor 7-like 2 (T cell specific, HMG-box) [TCF7L2], insulin receptor substrate 1 [IRS1], nitric oxide synthase 1 (neuronal) adaptor protein [NOS1AP], and solute carrier family 30 (zinc transporter), member 8 [SLC30A8]). In addition to these three major classes, we also review the available evidence on novel genes (CDK5 regulatory subunit associated protein 1-like 1 [CDKAL1], insulin-like growth factor 2 mRNA binding protein 2 [IGF2BP2], potassium voltage-gated channel, KQT-like subfamily, member 1 [KCNQ1], paired box 4 [PAX4] and neuronal differentiation 1 [NEUROD1] transcription factors, ataxia telangiectasia mutated [ATM], and serine racemase [SRR]) that have recently been proposed as possible modulators of therapeutic response in subjects with T2DM.

Type 2 diabetes in pediatrics and adults: thoughts from a clinical pharmacology perspective

Type 2 diabetes results when insulin secretion is unable to keep the plasma glucose levels as per acceptable range. This leads to chronic hyperglycemia and its associated microvascular complications such as renal impairment (diabetic nephropathy), retinal abnormalities (diabetic retinopathy), and autonomic, sensory, and motor neuropathies (diabetic neuropathy) and macrovascular disease. Historically, type 2 diabetes is well known as an adult-onset disease; however, lately, the incidence of the disease is reported to be increasing in children. Despite the wealth of information concerning type 2 diabetes in adults, data unique to the pediatric age group regarding the pathophysiology and therapy for type 2 diabetes are limited. For treatment in pediatric type 2 diabetes, metformin and insulin are the only antidiabetic agents approved currently. There are data of use of other oral antidiabetic drugs including glimepiride, rosiglitazone, and glyburide (in combination with metformin) in pediatric patients; however, formal clinical trials to establish the safety and efficacy have not been conducted. This review will compare the clinical pharmacology aspects of the oral type 2 diabetic drugs in pediatric and adult populations in order to determine any differences between the two patient groups.

Alternative methods to a TaqMan assay to detect a tri-allelic single nucleotide polymorphism rs757210 in the HNF1β gene

BACKGROUND

Several studies report difficulties in genotyping HNF1β rs757210 using TaqMan probes. This is possibly due to the tri-allelic nature of this single nucleotide polymorphism (SNP). The aim of the present research was to develop alternative methods for genotyping rs757210.

METHODS

Pyrosequencing and high resolution melting analysis of small amplicons (HRM) were developed and tested in panels of type 2 diabetes mellitus patients (n=258) and healthy blood donors (n=183). Results were confirmed by Sanger sequencing.

RESULTS

With pyrosequencing, allele frequencies for the A, G and C allele of 0.42, 0.56, 0.02 and 0.37, 0.62, 0.01 were established in the panel of type 2 diabetes mellitus patients and healthy blood donors, respectively. Similar results were found using the more routinely available HRM method. Results for pyrosequencing and HRM were in 99.6% concordance.

CONCLUSIONS

Pyrosequencing and HRM can be used to genotype the tri-allelic SNP rs757210 in the HNF1β gene and have the advantage over the commercially available TaqMan analysis that they can determine the rare C-allele variant.

Exogenous glucagon-like peptide-1 attenuates the glycaemic response to postpyloric nutrient infusion in critically ill patients with type-2 diabetes

INTRODUCTION

Glucagon-like peptide-1 (GLP-1) attenuates the glycaemic response to small intestinal nutrient infusion in stress-induced hyperglycaemia and reduces fasting glucose concentrations in critically ill patients with type-2 diabetes. The objective of this study was to evaluate the effects of acute administration of GLP-1 on the glycaemic response to small intestinal nutrient infusion in critically ill patients with pre-existing type-2 diabetes.

METHODS

Eleven critically ill mechanically-ventilated patients with known type-2 diabetes received intravenous infusions of GLP-1 (1.2 pmol/kg/minute) and placebo from t = 0 to 270 minutes on separate days in randomised double-blind fashion. Between t = 30 to 270 minutes a liquid nutrient was infused intraduodenally at a rate of 1 kcal/min via a naso-enteric catheter. Blood glucose, serum insulin and C-peptide, and plasma glucagon were measured. Data are mean ± SEM.

RESULTS

GLP-1 attenuated the overall glycaemic response to nutrient (blood glucose AUC30-270 min: GLP-1 2,244 ± 184 vs. placebo 2,679 ± 233 mmol/l/minute; P = 0.02). Blood glucose was maintained at < 10 mmol/l in 6/11 patients when receiving GLP-1 and 4/11 with placebo. GLP-1 increased serum insulin at 270 minutes (GLP-1: 23.4 ± 6.7 vs. placebo: 16.4 ± 5.5 mU/l; P < 0.05), but had no effect on the change in plasma glucagon.

CONCLUSIONS

Exogenous GLP-1 in a dose of 1.2 pmol/kg/minute attenuates the glycaemic response to small intestinal nutrient in critically ill patients with type-2 diabetes. Given the modest magnitude of the reduction in glycaemia the effects of GLP-1 at higher doses and/or when administered in combination with insulin, warrant evaluation in this group.

TRIAL REGISTRATION

ANZCTR:ACTRN12610000185066.