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Prevalence and prevention - Albert Cilia-Vincenti

Doctors George Debono and Jean Karl Soler have argued about the prevalence of type 2 diabetes in Malta, while MEP and lawyer Francis Zammit Dimech has been pushing our health authorities to provide free continuous blood glucose monitors and needles (August 24).

As a pathologist I’m not particularly interested in these monitors or needles. I am mainly interested in disease causation and evolution, from which one might infer how to diagnose it earlier and whether it is preventable or reversible.

Continuous glucose monitors and needles are obviously important for insulin-dependent diabetics, but these individuals have end-stage disease because their insulin-producing part of their pancreas has been destroyed by autoimmunity or bad genetics and bad diet.

To his credit, Zammit Dimech recognises the importance of research and attempts at preventing diabetes type 2. The Debono and Soler debate about prevalence really depends on what criteria are used to establish the disease state of “early diabetes”. 

In conventional medicine this early stage of the disease is termed “prediabetes”.  Many interpret that as “not diabetes yet”, which is essentially a “false negative” diagnosis – that is, a wrong diagnosis, because type 2 diabetes has in fact commenced. This is potentially a controversial area of diabetology because of its profound consequences on diabetes type 2 prevalence assessment.

The authoritative US Centers for Disease Control and Prevention recently claimed that blood sugar levels of more than one in three American adults are too high, including prediabetics in their statement.

In 2016, the University of California, Los Angeles, claimed that 55 per cent of Californian adults are either prediabetic, diabetic, or have undiagnosed type 2 diabetes.  Prediabetes is not a concept but a real disease state. There is enough published evidence that damage to kidneys, eyes, nerves, blood vessels and increased cancer risk often starts during prediabetes. 

There currently appears to be a number of important awareness problems. One of them is that a significant section of the global medical community may have failed to recognise the life-shortening impact of prediabetes. Another awareness problem is that the goalposts for safe blood glucose levels have been changing.  Levels considered dangerous now were thought to be safe decades ago. A third problem is that prediabetes and early stage diabetes may be missed by the standard fasting blood glucose test.

A significant section of the global medical community may have failed to recognise the life-shortening impact of prediabetes

The haemoglobin A1c (HbA1c) blood test provides a better picture of blood sugar control than fasting blood glucose, but is probably underutilised in identifying prediabetes. The safe upper limit for HbA1c is considered 5.5 per cent. A repeated HbA1c between 5.6 and 6.4 per cent diagnoses prediabetes. 

Perhaps the term prediabetes is a misnomer because even modestly elevated glucose levels inflict small blood vessel damage resembling the long-term complications of type 2 diabetes. Excess blood sugar is inflammatory to many tissues, including arteries, which contributes to heart attacks and strokes. High “normal” blood sugar levels are increasingly recognised as posing an increased risk of degenerative disorders, including dementia.

Fasting blood glucose values in the upper “normal” range (above 4.7mmol/L) have recently been claimed to be an important independent predictor of cardiovascular death in nondiabetic apparently healthy middle-aged men.  After-meal glucose levels seem to be an even stronger predictor of disease risk.

About 70 per cent of pre-diabetics are estimated to develop full blown type 2 diabetes in their lifetime.  It is misleading to think that prediabetes means before diabetic damage is inflicted.  Coronary heart disease risk, for example, has been claimed to be similar between prediabetics and type 2 diabetics.

Early detection of prediabetes means a greater likelihood of reversing it before it progresses to established type 2 diabetes. Blood sugar-lowering approaches should therefore be initiated when HbA1c exceeds 5.5 per cent and not delayed till it reaches 6.5 per cent. The serious problem we have in this regard is that HbA1c is quoted as “normal” up to 6.5 per cent in most Maltese laboratories, including the one at the teaching hospital. 

Metformin has been recommended when the HbA1c is between 5.6 and 6.4 per cent to prevent type 2 diabetes from getting fully established, together with advice on calorie restriction (particularly the high glycaemic ones). Metformin enhances the function of the natural insulin secreted by the pancreas and functions via several mechanisms to improve blood sugar control. 

It has proven ability to delay or prevent type 2 diabetes. Yet recent American surveys reveal it is prescribed to only 3.7 to 8.1 per cent of prediabetics. Could the situation in Malta be similar? 

Metformin is a 40-year-old drug, originally of plant origin, and now very cheap.  There are very few medicines nowadays which are so effective and cheap. There is some controversy whether newer very expensive drugs exceed metformin’s performance in early diabetes type 2, but the proponents tend to be paid consultants to the pharmaceutical firms pushing the new expensive drugs. 

In the area of laboratory predictive testing for cardiovascular risk, we have probably underestimated the importance of the prediabetic state (as defined by HbA1c levels above). For around 60 years we’ve been totally taken up by the claims of a direct relationship between blood cholesterol, dietary saturated fats and heart attacks. 

Blood sugar may be a more important damaging inflammatory agent than dietary saturated fats and blood cholesterol. The French have the lowest heart disease mortality in Europe (and second lowest worldwide). Malta has almost three times the heart disease mortality of France. 

The reason for this is not likely to be Maltese consumption of dairy produce and meats being three times that in France. Blood sugar levels might be the problem, rather than cholesterol. Perhaps about half our adult population, like that in California, is prediabetic or already diabetic. Who knows?

(A fully referenced version of this article will be published in October in Synapse, a Maltese medical journal.)

Albert Cilia-Vincenti is a practising pathologist, a former scientific delegate to the European Medicines Agency and former pathology services director to the British and Maltese health services.

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