OGTT for Identifying Diabetes in Chronic Heart Failure

Oral glucose tolerance tests may be more useful than HbA1c in chronic heart failure patients…. 

In this prospective, observational study, researchers examined determinants of glucose tolerance in regards to body composition and skeletal muscle strength. Inclusion criteria included a diagnosis of chronic heart failure for at least 6 months, patients who were not on glucose-lowering medications and patients considered generally stable for 3 months prior to the start of the study. Study participants were given a 2-hour oral glucose tolerance test, with muscle strength and body composition assessed using isometric strength testing of the upper leg and dual energy x-ray absorptiometry. Researchers further assessed health-related quality of life and physical activity level using a questionnaire.

A total of 56 participants were analyzed with 55% classified as pre-diabetic, 14% as diabetic, and 20% as normal glucose tolerant. Univariate mixed model analysis showed 6 possible variables for explaining the observed glucose curves from the glucose tolerance test. These included: ischaemic etiology, daily physical activity, E/E’ ratio (ratio of mitral peak velocity of early filling to early diastolic mitral annular velocity), fat trunk/fat limbs and 90 degree angle knee extension strength.

Correlations between fasting insulin and both body mass index and fat mass/height² were found (r = 0.51, P < 0.0001). Fasting insulin was also related with total body fat, triglycerides and quadricep strength at 45 degrees (r = 0.49, P=0.0001; r = 0.39, P < 0.01; and r = - 0.33, P = 0.01). E/E’ ratio and fat distribution also showed an interaction effect with glucose curve, with multiple imputation analysis having the same results. This was related to body composition and left ventricular end-diastolic pressure, but not to severity of heart failure symptoms, severity of left ventricular dysfunction, nor typical medical therapies.

Health-related quality of life was similar among all groups as well as overall self-rated health status (Normal glucose tolerance: 7.0, pre-diabetics: 6.7, diabetics: 6.4; P = 0.90). Reported daily physical activity did not differ among groups.

Despite having near-normal fasting blood glucose levels, researchers found that the majority of stable chronic heart failure patients had impaired glucose tolerance; 79% of newly diagnosed diabetic patients were diagnosed due to 2-hour glucose values alone. Only 21% of study participants in this study with diabetes would have been correctly classified using fasting glucose values alone and none by using HbA1c.

• It is not uncommon for chronic heart failure patients to have glucose intolerance, associated with fat distribution and left ventricular end-diastolic pressure
• 2-hour oral glucose tolerance tests may be more effective for diabetes screening in this patient population than HbA1c tests and fasting blood glucose
• Further, large, randomized prospective studies are needed to confirm findings of this study and the potential clinical implications

Stevens AL, Hansen D, Vandoren V, et al. Mandatory oral glucose tolerance tests identify more diabetics in stable patients with chronic heart failure: a prospective observational study. Diabetol Metab Syndr. 2014;6(1):44. https://www.dmsjournal.com/content/6/1/44