Diabetes Mellitus

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Diabetes MellitusDiabetes mellitus is a condition which is characterized by high blood sugar levels, resulting from shortage of insulin production (Type I), or defects in insulin action on its target organs (Type II). Blood sugar levels in the body are tightly regulated by the hormone called insulin. Insulin is produced by the pancreas, and under healthy conditions, it keeps glucose levels within normal levels. In Singapore, about 1 in 12 adults is diabetic, of which 85-90% are of the Type II variety.

Eating increases glucose levels. This stimulates the pancreas to produce insulin which acts to reduce glucose levels back to normal. In patients with diabetes, the insufficient production of insulin, or the resistance of the body's cells to the action of insulin (insulin resistance) will cause glucose levels to remain elevated.



Type I Diabetes:

Type I diabetes is also known as insulin dependent diabetes, or juvenile onset diabetes. Generally occurring in children and young adults, the immune system of the body mistakenly produces antibodies that attacks the pancreas. The damaged pancreas becomes incapable of producing sufficient insulin. Insulin injections are required in Type I diabetes.

Type II Diabetes:

Also referred to as non-insulin dependent diabetes, or adult onset diabetes. In this condition, the pancreas can still produce insulin, but the body's cells fail to use insulin properly. Over time, there is also a steady decline in insulin production by the pancreas, meaning that some patients with Type II diabetes may eventually require insulin therapy.

Gestational Diabetes:

In this type of diabetes, blood sugar levels are raised during pregnancy and usually resolve once the baby is born.  However, 25-50% of women with gestational diabetes may eventually develop Type II diabetes later in life.

“Pre-Diabetic” Conditions:

Impaired Glucose Tolerance (IGT) and Impaired Fasting Glycaemia (IFG).


Diabetes mellitus is one of the top few chronic diseases in Singapore and most of the developed world.

Risk factors for developing diabetes are as follows:

• Family history of diabetes

High blood pressure


• Sedentary lifestyle

• Ethnic group – type II diabetes more common in Indians and Malays

• Above 40 years of age

• Smoking

• Pregnancy

• Previous gestational diabetes

• Pre-diabetic conditions (IGT and IFG)


Many people with diabetes do not have any symptoms, meaning that it can go undetected for many years.  This is especially so in those with Type II diabetes, gestational diabetes and the pre-diabetic forms.  It is therefore important to have yourself screened for diabetes.

In those with significantly high blood sugar levels, the symptoms may include:

• increase in amount and frequency of urination, including waking up at night to pass urine

Symptoms of diabetes• increased hunger and excessive thirst

• weight loss despite eating well

• tingling or numbness in the hands and feet

• fatigue

• blurred vision

• slow-healing skin wounds

• frequent infections


Over time, high blood glucose levels cause damage to the nerves and blood vessels (both large and small), leading to damage to the various organs.


Acute complications are generally related to acutely high or low blood glucose levels.

Diabetic Ketoacidosis – (glucose levels are very high)
This occurs when there is insufficient insulin to convert glucose into energy. The result is that the body then uses fat as an energy source. This produces ketones, a substance which is harmful to the body.

Symptoms include severe thirst, passing large volumes of urine, fatigue, nausea and vomiting, often together with abdominal pain. This condition requires immediate medical attention.

Hypoglycaemia – (glucose levels fall below 4.0 mmol/L)
This usually occurs either when diabetic medication dose is too high, or if there is insufficient caloric intake or sudden excessive physical exertion.

Symptoms of hypoglycaemia include dizziness, confusion, weakness, tremors, sweating and anxiety. Severe hypoglycaemia can lead to coma, seizures and irreversible brain death.


Chronic complications are related to damaged nerves and blood vessels, which occur slowly over time.

Eye complications (Diabetic Retinopathy):
Diseased small blood vessels cause leakage of protein and blood in the retina. Small aneurysms and new but brittle blood vessels (neovascularization) can also occur. Spontaneous bleeding from these abnormal blood vessels can compromise vision. Cataracts and glaucoma are also more common in diabetics. A person with diabetes is 25 times more likely to become blind compared to a non-diabetic.

Kidney complications (Diabetic Nephropathy):
Initially, there is leakage of protein in the urine. Later on, there may be progress to renal failure, in which the kidneys can no longer cleanse and filter the blood. When this happens, dialysis will be required.

Nerve damage (Diabetic Neuropathy):
Symptoms of nerve damage include numbness, burning and aching of the feet and lower limbs. This can eventually lead to the so called “diabetic foot”. The loss of sensation leads to the failure of recognizing and protecting the foot from injury. Because of poor blood circulation, minor injuries may not heal and serious infections can occur. Diabetes is the top cause of lower limb amputations.

Nerve damage can also cause erectile dysfunction and gastroparesis (delayed emptying of the stomach).

Accelerated atherosclerosis:
This hardening and narrowing of large blood vessels (atherosclerosis) can lead to coronary heart disease (angina and heart attacks), strokes and claudication (pain in the legs on walking due to reduced blood supply to the legs).



Your doctor will make the diagnosis of diabetes if either one of the following criteria are met:

1. In the presence of clearly elevated glucose levels with acute hyperglycaemic complications (ie. Diabetic ketoacidosis, hyperosmolar non-ketotic hyperglycaemic coma), no further tests are needed for diagnosis.

2. If you have typical symptoms of diabetes, then a single blood test confirming either one of the following will suffice:

• random blood glucose levels > 11.1 mmol/L,

• fasting blood glucose levels > 7.0 mmol/L or

• 2 hour post-challenge (the Oral Glucose Tolerance Test) glucose of
> 11.1 mmol/L

3. If you do not have the typical symptoms of diabetes, then you will need 2 blood tests on separate occasions both showing glucose levels beyond the ranges stated above.




There is clear evidence that diet control and weight loss in obese Type II diabetics, leads to improved carbohydrate metabolism, thereby reducing the amount of medication required to control glucose levels. Special attention should be paid to periods of illness, exercise and travel. Diet planning by a professional should be sought, but as a general guide:

• Diet should include foods from each of the basic food groups.

• Saturated fats less than 10% of total calories.

• Carbohydrates 50-60% of total calories.

• Protein 15-20% of total calories.

• Consume 20-35 g of dietary fibre from a variety of food sources.

• Diet should contain adequate vitamins and minerals.

• Cholesterol limited to <300 mg per day.

• Sodium intake limited to < 2 g per day if hypertensive as well.

• Abstain from alcohol.

• Use of artificial sweeteners within safe limits.


Maintain a sensible exercise plan to suit your age, aptitude, fitness and interest. Your doctor will often do a pre-exercise evaluation. If you have not been exercising for a while, start off slowly then build up intensity and duration as your fitness level improves.

Exercise in DiabetesGuidelines For Exercise:

• Frequency : 3-5 days per week (daily if exercise of low intensity)

• Intensity : 60-85% of maximum heart rate (or until you feel warm and sweaty)

• Duration: 20-60 minutes each time

• Type: Aerobic exercises such as brisk walking, jogging, cycling, swimming


Precautions For Diabetics When Exercising:

• Use proper footwear to reduce chance of blisters and other foot injuries

• Adequate hydration before, during and after exercise

• Avoid exercise during periods of acute illness or if severely hyper or hypoglycaemic

• Dose of medication may have to be reduced prior to exercise. This should be discussed with your doctor

• In patients with severe diabetic retinopathy, activities such as weight-lifting and heavy competitive sports should be avoided.


Oral diabetic medication helps control blood sugar levels in those whose bodies are still able to produce some insulin.  Remember, from our previous discussions, type II diabetics either don't make enough insulin, or have tissues with increased resistance to circulating insulin (or a combination of both).

Over time, type II diabetics may develop into what is known as "beta-cell failure" - when the beta cells, which are responsible for insulin production, can no longer produce insulin.  When they reach this stage, they will have to depend on insulin injections, either in combination with oral diabetic medication, or on its own.



 Sulphonylurea Secretagogues
(tolbutamide, glibenclamide, glipizide, gliclazide, glimepiride)

 Stimulates pancreatic insulin secretion and release.

(nateglinide, repaglinide)

 Stimulates pancreatic insulin secretion and release.


 Decreases production of glucose by the liver and makes muscle tissue more sensitive to effects of insulin.

 α-Glucosidase Inhibitors

Blocks breakdown of starches in the intestine, thus reducing rise in blood glucose levels after a meal.

(rosiglitazone, pioglitazone)

Helps insulin work better in muscle and fat, and reduce glucose production in the liver.

SGLT2 Inhibitors

Sodium glucose transporter 2 (SGLT2) works in the kidney to reabsorb glucose.  SGLT2 inhibitors block this action, causing excess glucose to be eliminated in the urine.

DPP-4 Inhibitors
(Sitagliptin (Januvia), linagliptin (Tradjenta))

Glucagon increases blood glucose levels, and DPP-4 inhibitors reduce glucagon and blood glucose levels.

(rapid-acting or long acting insulin)

Replaces the deficient insulin.




It is important to discuss appropriate targets for control with your doctor.  Knowing your treatment goals would allow you to more actively participate in managing your diabetes.

1. Targets For Glucose Control:


 HbA1C (%)

Pre-meal Glucose

 2-hour Post-meal Glucose (mmol/L)

(non-diabetic levels)

4.5 - 6.4

 4.0 - 6.0

 5.0 - 7.0

(target for most patients)

6.5 - 7.0

 6.1 - 8.0

 7.1 - 10.0

(adequate for some patients)

 7.1 - 8.0

 8.1 - 10.0

 10.1 - 13.0

(action need in all patients)

 > 8.0

 > 10.0

 > 13.0


2. Targets For Co-existing Hypertension in Diabetics:

Blood pressure target for diabetics should be < 130/85 mmHg.


3. Targets for Co-existing Hyperlipidaemia in Diabetics:

•  LDL-cholesterol target:  < 2.6 mmol/L
•  Triglyceride target:  < 1.7 mmol/L
•  HDL-cholesterol target:  > 1.0 mmol/L

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Further Reading

The article above is meant to provide general information and does not replace a doctor's consultation.
Please see your doctor for professional advice.