Diabetes is characterised by high levels of sugar (glucose) in the blood. It is a chronic disease, that if not managed well, would lead to other health conditions such as heart disease, kidney failure and blindness.

How is diabetes diagnosed? What are the differences between Type 1 and Type 2 diabetes? Is diabetes reversible?

Dr Teh Ming Ming, Senior Consultant from the Department of Endocrinology at Singapore General Hospital (SGH), a member of the SingHealth group, tackles your queries on diabetes.

Question from c******

Dear Dr Teh, is it true that prolonged intake of avorstatin can cause diabetes in some patients? My dad has been prescribed avorstatin since last year to manage his cholesterol but I read that a side effect of taking it is type 2 diabetes. If this is true, is there anything he can do to minimise the risk? He's also on medication for blood pressure.

Answered by Dr Teh:

There have been various studies looking at the link between statin use and diabetes but no definite conclusion has been drawn. It may not be easy to settle the issue once and for all. Many of the patients with high cholesterol and high blood pressure are at risk of developing diabetes. On a more practical note, lifestyle changes should help to reduce the risk of developing diabetes. Hence, it is important that your father has a healthy diet and exercises regularly in order to reduce the risk of developing diabetes.

Question from g************

Dear Dr Teh,

My blood glucose is well controlled, sometimes I feel nauseous and experience symptoms of hypoglycemia after exercising. Usually I have a snack before exercising, so I’m not sure what is causing these symptoms. May I know how often I should test my blood sugar, and what should I do if it is too high or too low?

Thank you!

Answered by Dr Teh:

I would recommend at least checking your fasting blood glucose in the morning if you are on once daily insulin injection. I would advise you to check the evening blood sugar before dinner too if you are on twice daily premixed insulin injection such as Novomix 30 or Mixtard 30 which is the common premixed insulin preparations in Singapore. On the other hand, if your insulin regimen consists of injecting once daily long-acting insulin together with short- acting insulin before each meal, I would advise you to check blood sugar before your meals and at bedtime in addition to the morning fasting blood glucose.

Moreover, I would also advise you to check your blood before exercise and after exercise. Typically, we consider blood sugar below 4 mmol/l as low blood sugar. If you are regular experiencing episode of blood sugar below 4 mmol/l after exercising, I would advise you to have a carbohydrate rich snack to boast your blood sugar before exercise. If you find that blood sugar is running low after the exercise, you can have sugary drinks to bring your blood sugar up. There may be other strategies available in preventing low blood sugar after exercise but this very much depends on your insulin regimens. You can discuss this with your doctor at your next diabetes outpatient clinic appointment.

It is difficult to advise you here exactly what to do if the blood sugar is too high as it depends very much on your insulin regimen. This is best done via a face to face consultation with your doctor who looks after you for your diabetes. One of the strategies which you can try is avoiding the food which pushes your blood sugar up in the first instance. If you have already tried avoiding food which pushes up your blood sugar but blood sugar level is still high, you can increase the doses of insulin injection. As there are various preparations of insulin available, it is difficult to standardise this piece of advice. I would advise you to discuss this with the doctor about how to adjust your insulin doses in response to the high blood sugar reading at your next diabetes clinic appointment.

Question from m*******

Dear Dr,

I have been told that there are signs of diabetic retinopathy in my eyes, and that I will have to get injections for my eyes. This worries me. Is diabetic retinopathy reversible? Many thanks in advance.

Answered by Dr Teh:

Injection treatment for diabetic retinopathy is beneficial for the eyes so it is important that you have the treatment as advised by your eye specialist. There are different types of diabetic retinopathy and some of them are not reversible. Fortunately, treatment for diabetes retinopathy can help to stop the damage to the eyes and may restore the vision in some cases. The equally important issue here is prevention of further sight-threatening diabetic retinopathy through good control of diabetes. You can improve your control of diabetes through combination of lifestyle changes and taking appropriate diabetes medications which are prescribed by your doctor.

Question from R*****

It has become a habit for me to eat at night (around say 11pm & after). This started when i used to exercise at night after work. If i don't eat, i may go hungry and it could affect my sleep.


  1. If i eat & sleep, would it cause a problem in term of my blood sugar level and my cholesterol level?
  2. what type of food/snack/supper should i eat before bed?

Answered by Dr Teh:

Your blood sugar and your cholesterol levels may be affected if you eat before bedtime. The resulting effects of eating on blood sugar and cholesterol depend largely on what has been eaten.

The best thing is to avoid eating before bedtime. As sleeping is associated with a prolonged period of inactivity so the energy expenditure is low during sleeping. Hence, the excess calories may be stored in the body and this in turn may promote weight gain. If one has to take snack before bedtime, the usual advice regarding healthy low calorie snack still applies.

Question from s***

Dear Dr Teh,

My granny is 82 years old and has been managing her diabetes well until recently. She’s been showing signs of dementia and last I visited her, she said her eyes are not so good and I saw her feet and toes look a bit dark. There are no bruises on her soles though. What can I do to take better care of her?

Answered by Dr Teh:

You can go along with your grandmother when she next attends the clinic appointment for her diabetes. Most polyclinics and hospitals offer eye screening to the diabetes patients annually to pick up eye changes associated with diabetes. Appropriate treatments or monitoring strategies can be deployed to tackle the changes in the eyes associated with diabetes. Similarly, most healthcare institutions also offer checking of the feet of the diabetes patients annually to make sure that the feet are fine. The blood vessels and the nerve fibres of the feet can be affected by poorly- controlled diabetes. This can manifest in the form of pain on walking or pain at night or recurrent foot ulcers which heal poorly.

Question from l****@ymail.com

Dear I was prescribed Simvastatin 10 mg (half tab per day) many years ago together with my diabetic medicine. My diabetes is under good management. My last two blood tests in March 2017 and Feb 2018 showed my cholesterol as 3.75 and 3.28 and triglycerides as 1.1 and 1.05. I asked whether I could discontinue with Simvastatin as I am retired and could better control my oily food intake and more exercise time. The doctor seems reluctant and continue to prescribe Simvastatin. Is it safe to continue with the medicine? Thank you.

Answered by Dr Teh:

It is generally safe to continue with continue to take Simvastatin. But you would need to pay attention to unusual musculoskeletal pain which is a rare side-effect of simvastatin.  However, most patients tolerate simvastatin well.

Question from j****

I’ve just been diagnosed as pre diabetes as my HBA1c result came in at 5.8. Plus my BMI at 23.5. I’m quite scared as I don’t want to get diabetes. The nurse told me I had to try to lose some weight and exercise a bit more. Plus cut some carbohydrates from my meals. If I do this diligently from now on, will it work and stop me from getting diabetes?anything else I should do to be definitely effective? Please help and advise me!! I heard somewhere that prediabetes is curable but diabetes is not...

Answered by Dr Teh:

I think the nurse's advice regarding healthy lifestyle is a piece of prudent advice. The Hba1c of 5.8% is close to the pre-diabetes Hba1c cut-off of 6-6.4%. The actual number is not that crucial but it is the long term of  progression of Hba1c into diabetes range which is worrying. Paying attention to diet and regular exercises help to prevent diabetes. Cutting down on   carbohydrates, salt and oily food  intake as well as regular exercises are all beneficial for health. There is everything to play for at this stage as lifestyle intervention may help to prevent progression to diabetes.

Question from S*

Dear Dr,

I am taking Metformin for my Diabetes Two each night. I take 2 separate tablets of 500 and 750 mg. Do these 2 tablets ( their combined dosage=1,250 mg) work in the same way as would a single table of 1,250 mg strength? Should I instead be taking this one table of 1,250 mg instead of 2? Thank you.

Answered by Dr Teh:

I do not think there is a major difference between the 2 methods of dosing of metformin as long as the dosages of metformin are the same.

Question from S*******

Dear Dr Teh,

I am happy to read from Healthxchange.sg that there is an opportunity to find out more about diabetes.

I am a male, 68+.

Last week, I took a Glucose Stress Test at Alexandra Hospital. The readings are:

Fasting: 6.7 

2 Hours: 8.4 

The week before, I reframed myself from sweet food and drinks, took less white rice, and took potato daily. Am I now diabetic?

How could I be seen by a Endocrinology Doctor in SGH?

Thank you very much.

Answered by Dr Teh:

You do not have diabetes at this moment in time. But your body is not handling the sugar load very well during the oral glucose tolerance test. Hence, your fasting blood glucose and 2 hour blood glucose values are higher than normal. All these translate into higher risk of developing diabetes in the future. Lifestyle interventions such as healthy diet and regular exercises are crucial in preventing diabetes.

You can ask your general practitioner or polyclinic doctor to refer you to SGH if you would like to be seen in SGH.

Question from j******

I have a fasting glucose test of 6.3 mmol/L. Am I considered to have prediabetes. What should I do to prevent it from becoming to full diabetes.

Answered by Dr Teh:

You have impaired fasting glucose level which is generally considered as pre-diabetes. Impaired fasting glucose occurs when blood glucose levels are elevated during periods of fasting but not high enough to warrant the diagnosis of diabetes. Essentially, the body is not able to handle or process the glucose as efficiently as it should be. People with impaired fasting glucose level are at risk of developing diabetes. Lifestyle modification such as healthy diet and regular exercise are important to prevent the progression from impaired fasting glucose to diabetes.

Question from D**


Hopefully you can help me or direct me to the information I need.

I am going to be visiting Singapore in May of this year and I was wondering what the rules and regulations are for travellers into Singapore in regards to carrying diabetes supplies on my flight over? Syringes, insulin, lancets, etc.? I can’t seem to find information on this on the internet?

Coming from Toronto, Canada.
Type 1 diabetic with an insulin pump.
Thanking you in advance for your assistance.

Answered by Dr Teh:

You can bring all your usual syringes, insulin, lancets and your pump accessories to Singapore. There is no restriction in bringing the appropriate quantities of the above items into Singapore if you explain to the custom officials about your medical conditions in the event that you are being asked about this. It would be advisable to bring a letter from your doctor regarding your diabetes and what you need to carry with you for treatment of your diabetes. Have a safe trip.

Question from J************

Dear Dr Teh, will like to check is type 2 diabetes reversible?

Answered by Dr Teh:

Early stages of type 2 diabetes are potentially reversible in the sense that diet and exercises may help to achieve good blood sugar control without the use of medications. Those people whose diabetes is potentially reversible tend to be those with very good diabetes control and on minimum diabetes medications.

Question from v********

After my evening meal, I would measure the 2-hr post meal blood glucose. It has usually been below 7 mmo/L. However, the fasting blood glucose in the morning sometimes go as high as 6.8 mmo/L. Daytime readings before and after meals are between 6 to 7 mmo/L. Why is the morning fasting blood glucose sometimes so much higher than the previous night's reading?

Answered by Dr Teh:

The liver does churn out glucose at night. This helps to maintain the blood glucose at a certain level in normal individual. Unfortunately, this tends to drive the blood sugar up in people with diabetes. Therefore, value of the morning blood sugar is not totally dependent on the blood sugar level the night before.

Question from f********** 

Dear doc,

I noticed that my glucose fasting result has been increasing. in 2015 it was 5.1, 2016 5.2, and 2018 5.5. Is this ok? What can i do to bring it down? Will I become diabetic soon?

Answered by Dr Teh:

Your fasting glucose is rising slowly. The risk of the progressive rise in fasting blood glucose level is that the level may go into the diabetes range in the future. Diet and exercises can help to bring down fasting blood sugar. The key is to prevent the progressive rise in fasting blood sugar into the diabetes range.

Question from S*********

Dear Dr Teh

Recently while I done my glucose level check notice that fasting level is alway around 10.7 and after meal glucose level is around 15-16 for the past one week. It’s worry me a lot and i don’t wish to start any medication as I heard that once medication kick off it’s not reversible. Do you think it’s advisable that I give myself a period of 6 months to adjust my lifestyle and diet to see any improvement before I consult GP?

I have start to do workout thru out the week and also take meal more regularly instead of skipping meal on and off or have super late dinner.

Answered by Dr Teh:

Lifestyle modification certainly helps to improve blood sugar control. I would advise you to discuss this with your doctor. Your doctor can organise fasting blood sugar or oral glucose tolerance test for you. Oral glucose tolerance test involves taking a sugary drink and check the blood glucose level before and 2 hours after taking the sugary drink. Formal testing of blood sugar by the laboratory is more accurate than the conventional finger prick blood test. I assume that you are using the finger prick blood test in this case. That should clarify the issue.

Question from E********

In Feb a day prior to my operation, blood was drawn from me upon admission and the doctor told me the glucose was very high and suspected I had diabetes. But my fasting glucose test in Jan 18 showed my glucose reading as 5.2 which was within the normal range. I was told I could have impaired glucose tolerance. How does impaired glucose tolerance happen and how can we prevent it?

Answered by Dr Teh:

Your fasting blood glucose of 5.2mmol/l is within the normal limit. Operation is associated with stress to the body which can drive the blood sugar up even in normal circumstances. It is not very clear to me whether you have impaired glucose tolerance. I would advise you to see your doctor to discuss this. Your doctor can perform a glucose tolerance test which involves taking a sugary drink and check the blood glucose level before and 2 hour after taking the sugary drink. That should clarify the issue.

Impaired glucose tolerance mean the blood sugar levels are raised above the normal levels but not high enough to warrant the diagnosis of diabetes. Diet and exercise can help to prevent impaired glucose tolerance.

Question from V*****

Dear doctor

I like to know how I can be sure I am diabetic. Last year my reading was 5.9 and my doc scare me that I'm pre diabetes. Since then I been worried. My dad was childhood diabetic taking insulin injections. How can I ensure i am not heading that way. Thank you for your kind reply.

Answered by Dr Teh:

Diet and exercises can help to reverse the pre-diabetes states to normal. Your fasting blood sugar of 5.9mmol/l is suggestive of pre-diabetes. There is everything to play for at this stage with lifestyle modification to prevent the progression to diabetes.

Question from S*****

Dear Sir,

I have type 2 diabetes since last 7 years. I have tried my best to remain safe in the lifestyle.
I want to know about the topic HBA1c. What is the meaning of this terminology? What is the safe limit of HBA1c? Kindly give your answer in detail in plain english.

Answered by Dr Teh:

Hba1c is an important test which gives an indication of how good your diabetes is being controlled. Hba1c refers to the percentage of red blood cells which is stuck with the sugar. The higher the blood sugar levels of a person have been, the higher will be the percentage of red blood cells which is stuck with the sugar and hence the higher Hba1c of the person. We would aim for Hba1c of 6.5% in majority of the diabetes patients.

Question from v********

I am pre-diabetic. I have 2 questions:

  1. Given that the liver can churn out glucose at night, is this a cause for concern?
  2. what can I do to manage this phenomenon?​

Answered by Dr Teh:

  1. No, it is not a cause of concern. The liver also churns out glucose in normal individuals. This helps to maintain a normal glucose level when the person has not eaten for some time for example overnight. The liver also responds to various hormones such as insulin which help to regulate the blood glucose level.
  2. Lifestyle modification with diet and exercise is the key to prevent the progression of pre-diabetes to diabetes. Exercises also help your own insulin to work better in bringing down the blood sugar. Overall, lifestyle medication delivers beneficial effects to the various cells and organs of our body in preventing the progression from pre-diabetes to diabetes.

Question from r*****

My husband has recently decided that he should cut his carbohydrate intake by half as he has heard all the stories about it being the risk factor for diabetes. But his sugar level is currently ok and he is a very active sportsman.

Then he says cut down on meat as well.

But he gets hungry all the time.

I’m confused. What should he eat anymore?

He’s getting paranoid and I don’t know what to cook!

Help with some practical advice please.

He’s turning 60 soon. Thanks much.

Answered by Dr Teh:

A balanced meal with right balance of carbohydrate, protein and fat is the key in maintaining good health. Carbohydrate is a form of fuel to the body. One possibility is that your husband is a very active sportsman and he does use up a lot of energy during his sport activities so he may need a bit more carbohydrate. That might explain why he is hungry all the time. He can increase his carbohydrate intake modestly if his carbohydrate intake is not sufficient to meet his energy expenditure. Some people try to increase fruit and vegetable intake while reducing the carbohydrate intake. The carbohydrate requirement is different for each person depending on the body build and the activities level.

About: Dr Teh Ming Ming

Dr Teh Ming Ming graduated from University College Dublin in 1997. He obtained his Membership of the Royal College of Physicians (UK) in 2002. He underwent his specialist training in Endocrinology and Internal Medicine at the Guy’s and St Thomas’ Hospital, London and King’s College London and was awarded his Certificate of Completion of Training (CCT) in 2009.

He has a keen interest in research and was awarded a doctorate of medicine by King’s College London in 2009, after a two and a half year research period under the auspices of Professor Stephanie Amiel, investigating the link between the effects of hypoglycaemia and higher brain function. The project was wholly funded by the Juvenile Diabetes Research Foundation (JDRF). Dr Teh has many publications in international peer-reviewed journals, textbooks and has presented his work at many international conferences.

His subspecialty interests are type I diabetes, hypoglycaemia and insulin pump therapy.

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