Changes in glucose metabolism in people with different glucose metabolism disorders at baseline: follow-up results of a Finnish national diabetes prevention programme

Aim To examine changes in glucose metabolism (fasting and 2-h glucose) during follow-up in people with impaired fasting glucose in comparison with changes in people with isolated impaired glucose tolerance, people with impaired fasting glucose and impaired glucose tolerance combined and people with screening-detected Type 2 diabetes at baseline, among those who participated in a diabetes prevention programme conducted in Finland. Methods A total of 10 149 people at high risk of Type 2 diabetes took part in baseline examination. Of 5351 individuals with follow-up >= 9 months, 1727 had impaired glucose metabolism at baseline and completed at least one lifestyle intervention visit. Most of them (94.6%) were overweight/obese. Results Fasting glucose decreased during follow-up among overweight/obese people in the combined impaired fasting glucose and impaired glucose tolerance group (P = 0.044), as did 2-h glucose in people in the isolated impaired glucose tolerance group (P = 0.0014) after adjustment for age, sex, medication and weight at baseline, follow-up time and changes in weight, physical activity and diet. When comparing changes in glucose metabolism among people with different degrees of glucose metabolism impairment, fasting glucose concentration was found to have increased in those with isolated impaired glucose tolerance (0.12 mmol/l, 95% Cl 0.05 to 0.19) and it decreased to a greater extent in those with screening-detected Type 2 diabetes (-0.54 mmol/l, 95% Cl -0.69 to -0.39) compared with those with impaired fasting glucose (-0.21 mmol/l, 95% Cl -0.27 to -0.15). Furthermore, 2-h glucose concentration decreased in the isolated impaired glucose tolerance group (-0.82 mmol/l, 95% Cl -1.04 to -0.60), in the combined impaired fasting glucose and impaired glucose tolerance group (-0.82 mmol/l, 95% Cl -1.07 to -0.58) and in the screening-detected Type 2 diabetes group (-1.52, 95% Cl -1.96 to -1.08) compared with those in the impaired fasting glucose group (0.26 mmol/l, 95% Cl 0.10 to 0.43). Results were statistically significant even after adjustment for covariates (P < 0.001 in all models). Conclusions Changes in glucose metabolism differ in people with impaired fasting glucose from those in people with isolated impaired glucose tolerance, people with impaired fasting glucose and impaired glucose tolerance combined and people with screening-detected Type 2 diabetes.