Type 2 diabetes managed by diet and lifestyle: HbA1c can identify significant post-prandial hyperglycaemia

Post-prandial hyperglycaemia is predictive of cardiovascular disease risk. Therefore, the International Diabetes Federation (IDF) recommends that 2-hour post-meal glucose should not exceed 7.8mmol/L. There are limited data regarding the extent of post-prandial hyperglycaemia in those with well-controlled type 2 diabetes and how this relates to HbA1c values.

Twenty-nine volunteers with diet-controlled type 2 diabetes were recruited (mean HbA1c 50mmol/mol [6.7%], SD 6.5 [0.6]); mean age 62 years [SD 5.8]; mean BMI 31.9kg/m2 [SD 5.3]), and underwent a three-day period of continuous glucose monitoring (CGMS) at home.

Compared with volunteers with an HbA1c >48mmol/mol (6.5%), those with an HbA1c ≤48mmol/mol (6.5%) – mean HbA1c 54 (7.1%) vs 44.9mmol/mol (6.3%), p8mmol/L (703.1 vs 338.5 min, p=0.01). HbA1c showed reasonable correlation with time spent with glucose >8mmol/L (r2=0.48, p
Even volunteers with reasonably well-controlled, diet-managed type 2 diabetes spent a large proportion (9/24 hours) of the day with glucose concentrations in excess of 8mmol/L, suggesting that implementation of the IDF guidelines presents a challenge in normal clinical practice. HbA1c was a good indicator of post-prandial hyperglycaemia.