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Specific situations: peritoneal dialysis

Peritoneal dialysis uses the patient’s peritoneal membrane to ex-
change fluids and dissolved substances. The dialysis fluid typically con-
tains a high concentration of glucose to ensure hyper-osmolality and
hence continuous ultrafiltration. This potentially exposes patients to a
significant glucose load that can cause difficulties for some patients
with type 2 diabetes. Although the risk of hypoglycaemia might ap-
pear to be diminished (as a result of continuous glucose availability),
in practice, attempts to match this glucose load with insulin, delivered
into the dialysate or subcutaneously, can sometimes lead to more brit-
tle control, especially initially. In general, patients on peritoneal dialysis
need 2-3 times the insulin they received before starting it, coordinated
with the strength of the bags as well as the dwell time. Intra-peritoneal
insulin has a number of advantages including a reduced frequency of
hypoglycaemic episodes. The recent development of glucose-free
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dialysate fluids can modify the risk of hypoglycaemia in some patients
with diabetes. Although insulin requirements are much lower, and some
studies have suggested reduced glucose variability, monitoring of glu-
cose levels may be confounded by the icodextrin used in the place of
glucose as the primary osmotic agent, which may give false glucose
readings in some patients. 35

Preventing hypoglycaemia in the clinic

In most cases, adjusting behaviours, the dose or timing of medications
and/or the targets of treatment can prevent recurrent hypoglycaemic
events. Selecting foods that meet individual glucose requirements
can also be useful. For example, low GI foods and products, such as
uncooked cornstarch, that ensure the slow delivery of glucose are
helpful to prevent lows during the night or after meals (post-prandial
hypoglycaemia). Sometimes having meals that provide more glucose
up front may be important, particularly after dialysis and in those who
are on fast-acting agents or insulin. Overeating or snacking to prevent
hypoglycaemia is never a sustainable solution, and should be discour-
aged. Coordination of physical activity with medication doses and di-
alysis is also important.

Because of the ever-present threat of hypoglycaemia, the rationale
for attempting even modest glycaemic control in patients with CKD is
somewhat precarious. It rests on the paradigm that maintaining glu-
cose levels as close as possible to physiological levels will result in im-
proved clinical outcomes. However, the evidence for this in diabetic
patients with CKD remains largely anecdotal and inconclusive. Cer-
tainly, glycaemic control correlates closely with morbidity and mortality

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