Diabetes Pathology

Diabetes Mellitus

Diabetes mellitus (DM) is a group of diseases characterized by a disrupted carbohydrate metabolism leading to elevated blood glucose levels (= hyperglycemia) and secretion of glucose in the urine (= glycosuria) as a result of insufficient production or functioning of the pancreatic hormone insulin, combined with a number of yet undefined predisposing factors. 

DM is not a pathogenic entity but a group of etiologically different metabolic defects. Chronic hyperglycemia causes long-term damage, dysfunction and failures of various cells, tissues and organs.

Long-term complications of diabetes are:
  • Macro-angiopathy: Ischemic heart disease (IHD), stroke, peripheral vascular disease (PVD) 
  • Micro-angiopathy: Retinopathy, nephropathy 
  • Neuropathy: Peripheral neuropathy, autonomic neuropathy 
  • Cataract 
  • Diabetic Foot 
  • Diabetic Heart 

Classification of Diabetes Mellitus
  • Type 1 Diabetes Mellitus, formerly known as insulin dependent diabetes mellitus (=IDDM) or juvenile-onset diabetes 
  • Type 2 Diabetes Mellitus, formerly known as non-insulin dependent diabetes mellitus (=NIDDM) or adult-onset diabetes 
  • Gestational Diabetes Mellitus (GDM) 

Prevalence of Diabetes Mellitus

Diabetes is emerging rapidly as one of the most serious health problems of our time. This silent epidemic claims more lives per year than HIV/AIDS and places a severe burden on healthcare systems and economies everywhere, with the heaviest burden falling on developing countries. Yet awareness of the global scale of the diabetes threat remains piteously low. 

Diabetes is a chronic, potentially debilitating and often deadly disease. In 1985, there were an estimated 30 million people with diabetes worldwide. In 2005, the disease affects more than 230 million – a six-fold increase in a generation – thus affecting 5–6% of the global adult population. If nothing is done this figure will exceed 350 million worldwide by 2025. 

Every 10 seconds 2 people get diabetes. Each year more than 6 million people develop the disease. 
Every 10 seconds a person dies from diabetes-related causes. Over 3 million deaths per year are directly tied to diabetes, and an even greater number die from cardiovascular disease made worse by diabetes-related lipid disorders and hypertension. Globally, diabetes is the fourth leading cause of death by disease.

How to prevent diabetes complications:

  • Get regular checks. It is important a patient sees his/her physician regularly to ensure his/her health. Every three months (minimum) a patient should go for a check-up of the HbA1c (Glycated haemoglobin) and to have his/her feet checked. 
  • Tight control of blood glucose: number one goal is to keep the blood glucose tightly controlled. 
  • Quit smoking. 
  • Control high blood pressure 
  • Eat healthy foods 
  • Get regular exercise 
  • Limit alcohol 
  • Take care to prevent infections 


The Diabetes Control and Complications Trial (DCCT) was launched by the National Institute of Diabetes, Digestive and Kidney Diseases (NIDDK) in 1981. 29 clinical centres in the United States and Canada, and 8 central laboratories and units participated in the trial. 

Since the discovery of insulin in 1921, the medical community debated the glucose hypothesis that the marked elevation of blood glucose (hyperglycemia) associated with diabetes mellitus was responsible for the development and progression of the microvascular complications of type 1 (or insulin-dependent) diabetes: retinopathy leading to blindness, nephropathy leading to end-stage kidney disease, and neuropathy leading to loss of sensation, ulceration and amputation. The DCCT was designed to definitively answer whether a program of intensive therapy aimed at near normal levels of glycemia, when compared to conventional therapy aimed at maintenance of clinical well being, would affect the risk of onset and progression of these complications. 

During the period 1983-1989, 1441 subjects were enrolled in the study; making it the largest ever conducted diabetes study. Half the subjects were assigned at random to intensive therapy and half to conventional therapy. All subjects were scheduled to be followed until the fall of 1993. However, the dramatic beneficial results of the trial lead to its termination one year early in 1992. 

Findings of the DCCT? 

Lowering blood glucose reduces risk:
Retinopathy → 76% reduced risk
Nephropathy → 50% reduced risk
Neuropathy → 60% reduced risk


  • The DCCT Research Group (1993). The effect of intensive treatment of diabetes on the development and progression of long-term complications in insulin-dependent diabetes mellitus. The New England Journal of Medicine 329: 977-986. 
  • The UN resolutions Unite for Diabetes Media Kit 2006
  • International Diabetes Federation; Diabetes Atlas Second Edition; 2003
  • World Health Organisation; Laboratory Diagnosis and monitoring of Diabetes Mellitus; 2002

Links to learn more: