Type-2 diabetes and cardiovascular disease (CVD) is four to six times more common in people of South Asian descent in the UK than in the white population. None of the established tools evaluating cardio-vascular risk is validated in the South Asian population, and this has led to the suggestion that 10 years should be added to the age of South Asian people when calculating CHD risk.
The central distribution of fat and most of the components that comprise the metabolic syndrome are more frequent in South Asians. Intra-abdominal fat is more strongly associated with insulin resistance and is therefore likely to be the key to the enhanced prevalence of the metabolic syndrome and type-2 diabetes in this population.
Centripetal obesity is already present at birth and during adolescence in south Asians, and central abdominal fat accumulates more rapidly in later life in this ethnic group than in the white population. Thus using BMI as a measure of obesity and cardiovascular risk has recently been shown to significantly underestimate their detrimental impact in South Asian patients.
The obese South Asian is more likely to be glucose intolerant than the obese white patient. It has been suggested that a BMI of 27.5 in South Asians is comparable to that of 30 in a white patient, or that South Asians should be assessed using waist circumference as opposed to BMI.
A recent meta-analysis has demonstrated that when compared with the general population, South Asians also participate in less physical activity and have lower levels of fitness.
Dyslipidaemia and BP
South Asians have higher levels of triglycerides, lower levels of HDL cholesterol and higher levels of LDL cholesterol than the white population.
Migrants from the Punjab region of the Indian subcontinent when compared to their siblings still living in the Punjab have a greater BMI, higher cholesterol, lower LDL cholesterol and higher fasting blood glucose levels.
The prevalence of hypertension in South Asians is comparable with white groups.
However, left ventricular hypertrophy, hypertensive retinopathy and hypertensive renal damage is twice as common in patients with hypertension and metabolic syndrome compared to patients with hypertension alone.
Therefore, given the overall greater prevalence of metabolic syndrome in South Asian patients, the risk of developing cardiovascular complications is clearly increased.
It is unlikely that type-2 diabetes has a purely genetic basis. South Asians constitute a diverse mix of ethnicity and hence genotype and phenotype, which markedly influences the overall prevalence of both diabetes and CVD.
Pakistanis and Bangladeshis have a significantly greater prevalence of diabetes compared to Indians.
Fasting and Ramadan
In diabetic patients, fasting during Ramadan can potentially cause significant metabolic perturbations. Those who are unwell or for whom fasting may lead to harmful consequences are exempt (The Holy Koran, Al-Bakarah, 183–5), but because fasting is one of the five pillars of the Islamic faith, many diabetic patients will fast.
A multinational study of 13 countries found that 43 per cent of Muslim patients with type 1 and 79 per cent of muslim patients with type-2 diabetes, fasted for at least 15 days during the month of Ramadan. Thus, during Ramadan, many patients with diabetes will fast, a reality that physicians must recognise and address by providing guidance and advice to allow safe, rather than unguided and hence unsafe, fasting.
All diabetic patients who wish to fast must be assessed of physical well-being, overall control of glycaemia, BP and lipids, and renal function.
Evaluation and advice
Assessments provide the medical practitioner with an opportunity to risk stratifying the patient and adjust their diet and daily drug regimen at Seher (sunrise; the beginning of the fast) and Iftar (sunset; the end of the daily fast) to minimise the risk of hyperglycaemia or hypoglycaemia.
Patients should be actively encouraged to self-manage their disease during Ramadan, learn the warning signs of hypoglycaemia and hyperglycaemia and test their blood glucose as necessary during the fast — patients must be reassured that taking a blood sugar test does not break the fast.
The advice provided should not only be clear, accurate and consistent, but should take into account the cultural and behavioural characteristics and language of each ethnic group. Patient leaflets should give advice about safe participation in feasting and fasting, especially during Ramadan, and a more general overview of living with type-2 diabetes.
Patients must try to limit their intake of high fat, sugar rich sweets when breaking the fast. For example, dates are commonly consumed at Iftar but should be limited to a maximum of three per day.
There is no danger of hypoglycaemia with metformin alone, but the timing and dosage of metformin should be changed to take one-third of the dose at Seher and two-thirds at Iftar.
The glitazones (rosiglitazone and pioglitazone) should be taken with or without food at Iftar and, for those on a combination drug, the dose should be adjusted to take one tablet at Seher and one at Iftar.
The morning and lunchtime dose of sulphonylureas should be taken at Iftar and any evening dose should be taken at Seher. Several studies have shown a number of drugs in this class to be safe and effective during Ramadan, including glibenclamide, glimepiride, gliclazide once daily and repaglinide.
Those prone to hypoglycaemia should be changed to a drug with the lowest risk of hypoglycaemia. For example sustained-release gliclazide has been shown to have a lower (50 per cent) rate of hypoglycaemia compared to glimepiride.
Repaglinide or nateglinide may be useful for fasting because of their short duration of action that allows them to be taken at Seher and Iftar.
Patients with type-1 diabetes and poor glycaemic control (HbA1c >10 per cent) who are prone to ketoacidosis or hypoglycaemia should be advised not to fast. For those who do decide to fast, it is of utmost importance that they understand they must continue taking insulin during Ramadan.
The dose of long-acting insulins (glargine or detemir) should be reduced by approximately 20 per cent to reduce the risk of hypoglycaemia and should be given with the evening meal. Insulin prandial analogues, lispro and aspart, may be more useful than regular neutral insulin during fasting for two main reasons: they act more immediately — onset of action approximately 15 minutes versus approximately 30 minutes and peak effect 30–90 minutes versus 2–4 hours — and their duration of action is less.
Therefore they are useful at Iftar, when a large meal is likely to be consumed, because they work more immediately and limit postprandial hyperglycaemia. They are also useful at Seher where their shorter duration of action limits the risk of hypoglycaemia during fasting.
For premix insulins the morning dose should be taken at Iftar and half of the evening dose should be taken at Seher.
Emergencies that might arise during fasting are related to either hypoglycaemia or hyperglycaemia. But a recent study from Turkey showed the most common reason for attendance at A&E during Ramadan
was hypertension and uncomplicated headaches and the number of admissions related to hyperglycaemia or hypoglycaemia did not increase.
Dr Asghar is medical registrar, Dr Greenstein is clinical research fellow and Dr Malik is senior lecturer and consultant physician at the division of cardiovascular and endocrine science at the Manchester Royal Infirmary, Manchester
This is an edited version of an article published in MIMS Cardiovascular. To receive MIMS Cardiovascular visit www.haymarket.co.uk/specials
South Asians are at a significantly increased risk of developing diabetes and cardiovascular disease.
Alternative risk stratification should be developed for this population and more aggressive treatment of their risk factors is advocated.
Safe fasting and feasting is possible for the majority of patients with type-2 diabetes, if they follow medical advice and actively self-manage their diet, exercise and drug regimen.
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