Research proposal sample

Research proposal sample

Diagnosis and Classification of Diabetes: An Overview

Abstract
Diabetes mellitus (DM) is a chronic metabolic disorder characterised by persistent hyperglycaemia that can occur in both fasting and postprandial states. The long-term elevation of blood glucose levels is linked to damage, dysfunction, and eventual failure of various organs, particularly the eyes, kidneys, nerves, heart, and blood vessels. With a growing global prevalence, diabetes poses a significant public health burden. This article outlines the diagnostic criteria, classification, complications, and current management strategies for diabetes, including screening guidelines and therapeutic interventions.

Introduction

Diabetes is defined as a metabolic condition marked by hyperglycaemia resulting from defects in insulin secretion, insulin action, or both. Chronic hyperglycaemia is associated with progressive damage to multiple organ systems. According to the International Diabetes Federation, the global prevalence of diabetes was estimated at 366 million in 2011, with projections suggesting an increase to 552 million by 2030 (Whiting et al., 2011).

Diagnostic Criteria for Diabetes

The diagnostic thresholds for diabetes have been standardised across major health organisations, including the World Health Organization (WHO), the American Diabetes Association (ADA), and the Canadian Diabetes Association (CDA):

• Fasting plasma glucose (FPG) ≥ 126 mg/dL (7.0 mmol/L) on at least two occasions

• 2-hour plasma glucose ≥ 200 mg/dL (11.1 mmol/L) following a 75 g oral glucose tolerance test (OGTT)

• Random plasma glucose ≥ 200 mg/dL (11.1 mmol/L) in the presence of classic symptoms

• HbA1c ≥ 6.5% (48 mmol/mol), provided the assay is standardised to DCCT criteria

HbA1c has recently been adopted not only as a monitoring tool but also as a diagnostic criterion due to its correlation with microvascular complications such as retinopathy (Mannarino et al., 2013).

Prediabetes and Metabolic Syndrome

Prediabetes is a precursor state to diabetes, involving either impaired fasting glucose (IFG) or impaired glucose tolerance (IGT):

• IFG (ADA): FPG between 100–125 mg/dL (5.6–6.9 mmol/L)

• IGT: 2-hour plasma glucose between 140–199 mg/dL (7.8–11.0 mmol/L) after OGTT

These states are associated with elevated risks of cardiovascular diseases and often coexist with other metabolic abnormalities, forming what is known as metabolic syndrome—central obesity plus two of the following: elevated triglycerides, low HDL cholesterol, high blood pressure, or raised fasting glucose (Alberti et al., 2006).

Classification of Diabetes

Diabetes is primarily categorised into:

1. Type 1 Diabetes Mellitus (T1DM): Autoimmune destruction of β-cells, leading to absolute insulin deficiency.

2. Type 2 Diabetes Mellitus (T2DM): Characterised by insulin resistance and relative insulin deficiency. It accounts for 90–95% of all diabetes cases.

3. Gestational Diabetes Mellitus (GDM): Identified during pregnancy, GDM may resolve postpartum or persist as type 2 DM.

4. Maturity Onset Diabetes of the Young (MODY): A monogenic form of diabetes with autosomal dominant inheritance.

5. Latent Autoimmune Diabetes in Adults (LADA): A form of type 1 diabetes with slower onset, often misdiagnosed as type 2.

6. Syndromic and Secondary Diabetes: Caused by endocrinopathies, mitochondrial disorders (e.g., MIDD), or certain neurologic conditions like Stiff Person Syndrome.

Neurological and Acute Complications

Severe metabolic complications include:

• Diabetic Ketoacidosis (DKA): A life-threatening condition typically seen in T1DM. Symptoms include polyuria, polydipsia, Kussmaul respiration, and confusion.

• Hyperosmolar Hyperglycaemic State (HHS or HONK): More common in T2DM, presenting with extreme hyperglycaemia, dehydration, and neurologic deficits.

• Neurologic syndromes such as C-H-BG (chorea, hyperglycaemia, basal ganglia syndrome), seizures, and visual disturbances may occur.

Screening and Diagnosis

Since many individuals remain asymptomatic for years, early screening is vital. Recommended tests include:

• Fasting or random glucose levels

• HbA1c (where appropriate)

• OGTT in borderline cases or at-risk populations

• Exclusions: Conditions like hemoglobinopathies may render HbA1c unreliable

Glycaemic Targets and Management

The DCCT and UKPDS trials demonstrated the benefits of tight glycaemic control. The ADA recommends maintaining an HbA1c of <7% (53 mmol/mol) for most adults unless contraindicated by comorbidities.

Pharmacological Interventions

• Type 1 DM: Requires immediate initiation of insulin therapy, typically via basal-bolus regimens.

• Type 2 DM: Begins with lifestyle modifications and metformin. Insulin is added if oral agents fail to achieve control.

• Oral hypoglycaemic agents: Include sulfonylureas, DPP-4 inhibitors, SGLT2 inhibitors, and thiazolidinediones.

• Insulin regimens: Range from once-daily long-acting insulins to multiple daily injections in complex cases.

Combination therapies are often effective in enhancing glycaemic control and limiting side effects such as weight gain.

Conclusion

The diagnosis and classification of diabetes involve a multifaceted approach integrating biochemical, clinical, and occasionally genetic markers. Effective screening and early intervention remain key strategies in preventing or delaying complications. With rising global prevalence, comprehensive and individualised management—supported by evidence-based guidelines—is essential for optimal outcomes in diabetic care.