Type 2 diabetes: an overview

ARTICLE

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Endocrinology

WHAT IS TYPE 2 DIABETES?

Type 2 diabetes is a heterogenous condition characterised by insulin resistance and a relative deficiency of insulin.

CAUSES

Insulin is a hormone the pancreas excretes, and controls blood glucose as follows:^1,2

The presence of glucose circulating in the blood triggers the pancreas to release insulin
Insulin circulates in the bloodstream, enabling glucose to enter the cells
The amount of glucose in the bloodstream decreases
In response to this decrease of insulin, the pancreas releases less insulin.

Type 2 diabetes results from two physiological problems:^2,3

On a cellular level, muscle cells, fat, and the liver become resistant to insulin. This results in elevated glucose in the blood circulation
The lack of function of the pancreas to produce enough insulin (to remove blood glucose from the blood stream) results in hyperglycaemia. Hyperglycaemia then leads to cardiovascular and renal disease and it affects the nervous and immune systems.

SYMPTOMS

Symptoms of type 2 diabetes develop slowly, as a result many patients do not experience symptoms. The following symptoms are signs of type 1 and type 2 diabetes:^1,2,3

Polydipsia
Polyuria
Polyphagia
Unintended weight loss
Fatigue
Blurred vision
Slow-healing wounds – especially on the peripheral areas
Frequent infections
Numbness or tingling in the hands or feet.

DIAGNOSIS

Type 2 diabetes is diagnosed, among other factors using the HbA1c test⁴. This blood test indicates the average blood glucose level for the past 2-3 months. Results are interpreted as follows:

< 5.7% is normal
5.7% to 6.4% is diagnosed as prediabetes
6.5% or higher on two separate tests indicates diabetes.

Diagnosis can further also entail the following tests:

Random blood glucose test: regardless of when a patient has eaten, a level of 11.1 mmol/L or higher suggests diabetes
Fasting blood glucose test: this test is taken after a patient has fasted for 8-12 hours before the test. A blood sample of:
< 5.6 mmol/L is normal
5.6 to 6.9 mmol/L is diagnosed as prediabetes
> 7 mmol/L or higher on 2 separate tests is diagnosed as diabetes
Oral glucose tolerance test: this test is done when the patient has not eaten for an amount of time and then drinks a liquid that has a high sugar content. Blood tests are then tested periodically for 2 hours. Results of:
< 7.8 mmol/L after 2 hours is considered healthy
7.8 mmol/L or higher, after 2 hours suggests diabetes.

Pharmacists can also render ‘add on’ services by encouraging patients to come and check their blood glucose, cholesterol levels as well as have their urine tested for albumin (related to renal function) at regular intervals.

TREATMENT

Medicines for type 2 diabetes include the following:^5,6,7

Biguanides e.g., metformin (generally the first medicine prescribed for type 2 diabetes)
Sulfonylureas/Sulphonamides/urea derivatives e.g., glibenclamide, glicazide, glimepiride (with or without metformin), glipizide, repaglinide
Thiazolidinediones e.g., pioglitazone
Meglitinides e.g., nateglinide, repaglinide
Alpha glucosidase inhibitors, e.g., acarbose
DPP-4 inhibitors e.g., vildagliptin (with or without metformin), sitagliptin (with metformin), saxagliptin
GLP-1 receptor agonists e.g., exenatide, liraglutide, dulaglutide and semaglutide
SGLT2 inhibitors e.g., dapagliflozin, empagliflozin canagliflozin (not available in SA yet)
Insulin therapy is sometimes added, as a last resort, but may also be considered if glucose targets are not met.
Other medications (which might be prescribed in addition to the above medication), include:
- Antihypertension and cholesterol-lowering medicines, as well as low-dose aspirin, to help prevent heart and blood vessel disease.

LIFESTYLE CHANGES

Healthy lifestyle changes may prevent type 2 diabetes^1,3. Some healthy lifestyle changes include:

Eating healthy foods: which contains less fat and calories and are higher in fibre, eating fruits, vegetables and whole grains
Exercising frequently
Losing weight
Avoiding long periods of inactivity.

TYPE 2 DIABETES AND THE INTERCONNECTED SYSTEMS: THE HEART AND KIDNEYS

Type 2 diabetes affects major organs, such as the cardiovascular and renal systems, among other organs. The management of diabetes and controlling blood glucose levels can decrease the risk of complications and other medical conditions².

Risks and complications include:

Cardiovascular system: an increase of the risk of heart disease, stroke, hypertension, and atherosclerosis
Kidney system: diabetes may lead to irreversible chronic kidney disease or end-stage kidney disease. This may require dialysis or a kidney transplant.

REFERENCES

Centers for Disease Control and Prevention (CDC). Diabetes. Available at: https://www.cdc.gov/diabetes/basics/type2.html - accessed: 02 June 2023
Mayoclinic. Type 2 diabetes. Symptoms and causes. Available at: https://www.mayoclinic.org/diseases-conditions/type-2-diabetes/symptoms-causes/syc-20351193 - accessed: 02 June 2023
World Health Organisation (WHO). Diabetes. Available at: https://www.who.int/news-room/fact-sheets/detail/diabetes – accessed: 01 June 2023
Steyn, L. SGLT2 inhibitors. South African Pharmaceutical Journal, 2018,85(1):72-75
Monthly Index of Medical Specialities (MIMS), 2023, May, Volume 63, No 4, Johannesburg: MIMS (a Division of Arena Holdings)
Rossiter, Dawn. South African Medicines Formulary. Ed. Dawn Rossiter. 12th ed. Rondebosch, South Africa: Health and Medical Pub. Group of the South African Medical Association, 2016. Print

ADDITIONAL READING MATERIAL:

Causes of blindness and vision impairment in 2020 and trends over 30 years, and prevalence of avoidable blindness in relation to VISION 2020: the Right to Sight: an analysis for the Global Burden of Disease Study GBD 2019 Blindness and Vision Impairment Collaborators on behalf of the Vision Loss Expert Group of the Global Burden of Disease Study Lancet Global Health 2021;9:e141-e160
Institute for Health Metrics and Evaluation. University of Washington. Global Burdon Disease Results. 2020. Global Burden of Disease Collaborative Network. Global Burden of Disease Study 2019. Results. 2020, available at: https://vizhub.healthdata.org/gbd-results/ - accessed: 02 June 2023
Saran, R, Yi Li, Robinson, B, Ayanian, J Balkrishnan, R, Bragg-Gresham,J, et al. US Renal Data System 2014 Annual Data Report: Epidemiology of Kidney Disease in the United States, American Journal of Kidney Diseases, 2015 Jul;66(1 Suppl 1):Svii, S1-305
Sarwar N, Gao P, Seshasai SR, Gobin R, Kaptoge S, Di Angelantonio et al. Diabetes mellitus, fasting blood glucose concentration, and risk of vascular disease: a collaborative meta-analysis of 102 prospective studies. Emerging Risk Factors Collaboration. Lancet. 2010; 26;375:2215-2222