Type 2 diabetes managed by diet and lifestyle: HbA 1c 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 HbA 1c values. Twenty‐nine volunteers with diet‐controlled type 2 diabetes were recruited (mean HbA 1c 50mmol/mol [6.7%], SD 6.5 [0.6]); mean age 62 years [SD 5.8]; mean BMI 31.9kg/m 2 [SD 5.3]), and underwent a three‐day period of continuous glucose monitoring (CGMS) at home. Compared with volunteers with an HbA 1c >48mmol/mol (6.5%), those with an HbA 1c ≤48mmol/mol (6.5%) – mean HbA 1c 54 (7.1%) vs 44.9mmol/mol (6.3%), p<0.0001 – had lower mean 24‐hour glucose levels (8.4 vs 7.2mmol/L, p=0.02), reduced fasting glucose concentrations (8.0 vs 6.6mmol/L, p=0.01), and spent less time with glucose concentrations >8mmol/L (703.1 vs 338.5 min, p=0.01). HbA 1c showed reasonable correlation with time spent with glucose >8mmol/L (r 2 =0.48, p<0.0001). 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. HbA 1c was a good indicator of post‐prandial hyperglycaemia. Copyright © 2012 John Wiley & Sons.