The Effects of Hypoglycaemia in People With Type 2 Diabetes

Type 2 diabetes is associated with increased risk of cardiovascular disease. Although the United Kingdom Prospective Diabetes Study (UKPDS) follow-up data suggested reduced macrovascular complications with tight glycaemic control, recent studies in people with type 2 diabetes failed to replicate these findings. Furthermore, all-cause mortality was found to be increased with strict glycaemic control in the Action to Control Cardiovascular Risk in Diabetes (ACCORD) study. The cause of the increased deaths remains unclear.

Strict glycaemic control is associated with increased risk of hypoglycaemia. Although, hypoglycaemia has traditionally been considered a complication of the treatment for type 1 diabetes, it has recently been recognised as a problem in people with type 2 diabetes particularly those on insulin therapy. In the ACCORD study, the risk of death was significantly increased in those with one or more episode of severe hypoglycaemia in both the strict and standard study treatment arms. As plasma glucose falls to below 4.0 mmol/L, a series of defence mechanisms occur, at an individualised glycaemic thresholds, to reverse hypoglycaemia including a rise in catecholamine levels. This may lead to hypokalaemia, prolonged QT interval, and cardiac arrhythmias. It may also lead to impaired cardiovascular autonomic function for up to 16 hours afterwards; increased inflammatory markers; platelet activation and promote vascular damage. As the majority of studies assessing the effects of hypoglycaemia on cardiovascular risk markers are conducted in people with type 1 diabetes and healthy controls, their findings may not necessarily be applicable to people with type 2 diabetes. In particular, the effects of hypoglycaemia on platelet function and thrombotic risk in people with type 2 diabetes require further clarification. In this study, we hypothesised that acute hypoglycaemia will result in platelet activation in people with type 2 diabetes to a higher degree than controls.

Inclusion criteria

• Healthy volunteers:

• Males or females
• On no medications except for the contraceptive pill and without medical illnesses in the last three months.
• Non-smokers
• 40 - 60 years of age.
• T2DM subjects:

• Males or females
• Diagnosis of T2DM
• 40 - 60 years of age
• HbA1C: 6.5 - 9.5%
• Duration of diabetes 1 - 10 years
• Diabetes treated with diet, or tablets only.

Exclusion criteria

• Healthy volunteers:

• Pregnancy
• Lack of contraception in women of child bearing age
• Chronic medical conditions
• Current smokers
• Evidence of ischaemia on ECG
• Drop attacks
• Alcohol or drug abuse
• Psychiatric illness
• Previous history of seizure
• Alcohol or drug abuse
• Type 2 diabetes subjects:

• Pregnancy
• Current smokers
• Recurrent episodes of hypoglycaemia
• Treatment with anti-platelet or anti-coagulation therapy
• History of ischaemic heart disease, stroke or peripheral vascular disease
• Epilepsy
• Drop attacks
• Evidence of ischaemia on ECG
• Insulin treated T2DM
• History of microvascular disease (retinopathy, nephropathy or neuropathy).
• Alcohol or drug abuse
• Psychiatric illness