Acid-base disturbance in diabetes

Unless suffering some unrelated acute/critical illness, diabetic patients are only usually submitted for arterial blood gas analysis if they are suspected of suffering diabetic ketoacidosis, the potentially life-threatening acute complication of diabetes that is almost invariably associated with severe hyperglycemia. Blood gas analysis in cases of diabetic ketoacidosis reveals metabolic acidosis. 

The notion that acid-base disturbance in diabetes is confined to metabolic (keto) acidosis, however, is challenged by the results of a recent clinical study that aimed to investigate the extent of acid-base disturbance in the generality of diabetic patients who are not suspected of suffering ketoacidosis. 

The study population comprised 210 adult diabetic patients (median age 69 years, range 31-89 years) who were attending a hypertension/renal disease outpatient clinic. Of the 210 patients, 187 were suffering type 2 diabetes and the remaining 23, type 1 diabetes. These were long-standing diabetics; on average diabetes had been diagnosed 15 years previously. 

All 210 patients had blood sampled for blood gas analysis, electrolytes and serum creatinine. On the basis of serum creatinine result each patient was assigned to one of three groups with differing level of renal function/dysfunction: group A comprised 114 diabetics whose serum creatinine (<106 µmol/L) indicated normal renal function; group B comprised 69 diabetics whose serum creatinine was in the range of 115-265 µmol/L, indicating very mild to moderately severe renal dysfunction; and group C comprised the remaining 27 diabetics, whose serum creatinine was in excess of 274 µmol/L. 

Blood gas analysis revealed an acid-base disturbance in 176 of the 210 patients; only 34 (16 %) had normal acid-base balance. The most common disturbance was metabolic alkalosis, present in 116 patients (74 in group A, 34 in group B and 8 in group C). 

Metabolic acidosis was found in 33 patients (7 in group A, 9 in group B and 17 in group C). Respiratory disturbance, predominantly respiratory alkalosis, was evident in 26 patients. Just nine of the 176 patients with an acid-base disturbance had high-anion-gap metabolic acidosis, consistent with a diagnosis of either ketoacidosis or lactic acidosis. 

The results of this study suggest that acid-base disturbance is extremely common and varied in its nature among patients with long-standing diabetes, and occurs even among those whose kidney function is preserved.

Read more about acid-base:

• On the relationship between potassium and acid-base balance
• Acid-base disturbance in COPD
• Acid-base and electrolyte disorders in CKD – a review article
• Acid-base changes during resuscitation from out-of-hospital cardiac arrest