7 History taking in patients with diabetes

Top tip

Diabetes diagnosis, duration, complications and accurate current treatment are all you need: focus on these. Look up any recent biochemistry and HbA1c on the hospital system.

• Don't use obsolete terms for diabetes diagnoses (see Chapter 1). At best they can mislead, at worst they present hazard. If you don't know the type of diabetes, describe it, for example, 'diabetes, onset age 35, insulin treated since diagnosis'. The formal diagnosis can be reviewed later if necessary
• Focus on treatment. If you are seeing a patient initially with their carer, you're much more likely to get the treatment correct - they may recall more accurately than the patient, be able to get a prescription record, or contact someone immediately who will know the patient's treatment
• Once the patient is out of the emergency department, you are increasingly unlikely to get their diabetes treatment correct
• A few minutes spent focusing on diabetes-specific history is much more important than filling in all the boxes of systems enquiry
• Look up the hospital pathology database for a recent HbA1c and renal function results (very likely requested by the patient's GP)

Eliciting a good diabetes history, like any medical history, should take no more than a few minutes, but focus on the things that really matter to the patient and their safety.

Type of diabetes/diagnosis (Chapter 1)

Critical:

• Don't use 'IDDM' or 'NIDDM'
• Don't write 'Type 1 diabetes' just because someone is insulin treated; most insulin-treated patients have Type 2 diabetes; conversely, don't write 'Insulin-treated Type 2 diabetes' just because the patient is older; there is, happily, now a large number of Type 1 patients in their 70s and 80s
• If this is Type 1 diabetes, ensure the patient has not missed and will not miss any insulin doses (ask, and if there is uncertainty get urinary and/or ketone measurements: ketosis = insulin deficiency)

Duration of diabetes

The 'pre-clinical' duration of Type 2 diabetes is 7-10 years - Type 2 diabetes therefore often presents with advanced diabetes complications. You can correctly state either 'Type 2 diabetes, diagnosed 1995' or 'Known duration of Type 2 diabetes 17 years'.

Type 1 diabetes nearly always has an acute clinical onset: the younger the age of diagnosis the more acute the onset. The autoimmune process becomes less intense with age, so Type 1 patients in their 30s and older with Latent Autoimmune Diabetes of Adult onset (LADA) may be controlled for a short time on tablets (the definition allows 6 months; see Chapter 8). Multiple factors conspire to make diabetes with onset in young adults a diagnostic and therapeutic challenge (Figure 7.1).

Figure 7.1 The spectrum of autoimmune diabetes. Five known variable domains interact to generate the broadening presentation of autoimmune diabetes in younger and middle-aged people.Source: Reproduced with permission of Professor David Leslie, St. Bartholomew's Hospital.

'Honeymoon' period (remission)

A period of variable duration (usually 9-12 months) after the clinical onset of Type 1 diabetes during which insulin requirements are low or very low (~0.3-0.5 U/kg/day, sometimes as low as 0.1 U/kg/day). This is a spontaneous partial remission, the pathophysiology of which is not understood. Despite the very low doses of insulin, patients in this period after diagnosis should still be regarded as insulin-deficient and ketosis-prone; do not discontinue insulin treatment.

Long-term Type 1 diabetes

Long-term survivors of Type 1 diabetes (>50 years duration) are as a group extremely insulin-sensitive, and have an average daily insulin requirement similar to people in honeymoon, that is around 0.5 U/kg/day. In a thin individual, this may amount to no more than about 4 units of insulin with meals, and 10 units of basal insulin. They are, nevertheless, fully insulin-requiring and ketosis-prone.

Duration of diabetes is associated with increasing risks of both micro-and macro-vascular complications. Type 1 patients rarely have microvascular complications within less than about 10 years of diagnosis, but Type 2 patients are frequently diagnosed at the same time as an acute admission with a vascular complication, especially ACS and stroke. Any patient with known diabetes duration >10 years needs careful consideration of complications.

Treatment (Chapter 24)

Oral hypoglycaemics (tablets)

Not usually a problem to identify, and none are critical in the early stages of admission. In sick Type 2 patients, try to establish whether they are currently taking metformin (always large white tablets) and in what dose because of the outside possibility of lactic acidosis.

GLP-1 analogues

Non-insulin injectable agents, usually taken once or twice daily, sometimes weekly - always with disposable pens. Some patients think of these agents as insulin - the pen devices for GLP-1 analogues and insulin look similar.

Insulin

Patients should carry insulin-identification cards (Figure 7.2) but usually don't (mostly because we do not consistently give them out or change them when insulin preparations are altered). All the major insulin companies supply them to hospitals, usually via diabetes specialist nurses. Overseas patients may take insulin preparations not available in the UK (see Chapter 20). Ask to see any home blood glucose monitoring records (1 mmol glucose ? 20 mg). Written diaries are usually more helpful in spotting diurnal patterns of glycaemic control, especially hypoglycaemia, than the simple chronological sequence of results stored by most blood glucose meters.

Figure 7.2 Insulin identification cards. Plastic, credit card sized. Patients would probably carry them if we bothered to give them out (and to change them when their insulin preparations are altered).

Establishing the patient's current insulin preparations and doses is critically important, but doing so can occasionally be frustrating and time-consuming. A key long-term aim of insulin treatment is patient autonomy, and many patients - including nearly all Type 1 patients - will adjust insulin dosing day-to-day and dose-to-dose according to CBG levels, activity, carbohydrate intake and intercurrent illness and stress. There may therefore be no written record of the patient's current insulin doses - anywhere. If there is a critical illness i.v. insulin will be needed; if there isn't, and you have no way of accurately establishing insulin doses in time for the next insulin dose, you may need to consider improvising an emergency insulin regimen (Chapter 23).

If the patient has any doubts about the details of their insulin treatment, ask accompanying people - carers, relatives, friends, children in the case of non-English speaking patients, and with permission look at all containers of medication (individual insulin pens tend to gravitate towards the bottom of carrier bags). You may only have one opportunity to do this before the patient is moved from the emergency department to a ward where they may need their first dose soon. Do not leave your ward-based colleague to sort out the problem. Box 7.1 outlines some key questions that will help identify broad types of insulin, and Figure 7.3 is a simple flow chart to help identify specific types of insulin.

Box 7.1 Key questions to help identify insulin regimens (see Chapters 20 and 21)

• Do you take diabetes tablets (ask specifically about metformin)?
• How many times a day do you take insulin?
• If once a day, then likely Type 2 diabetes, taking isophane (cloudy) or long-acting analogue (clear) - usually at bedtime
• If twice a day then probably a mixture (cloudy) taken before breakfast and evening meal; nearly always Type 2, but a few Type 1 patients use twice-daily mixtures
• If three times a day, then possibly a mixture (cloudy) before the three meals (usually Type 2)
• If four times a day, then if you don't know otherwise, assume the patient has Type 1 diabetes (regardless of age, ethnicity or BMI) - even though basal-bolus insulin is used in Type 2 diabetes
• Have you taken or been given your insulin doses today?
• When was the last time you had your insulin?
• Is it cloudy insulin (isophane or biphasic insulin)?

Figure 7.3 Identifying insulin preparations based on the frequency of injections. If the patient is taking non-insulin diabetes drugs, then they very likely have Type 2 diabetes.

Complications

Retinopathy

Is the patient under the supervision of the hospital eye clinic? If so, there is either significant retinopathy - proliferative or maculopathy - requiring current treatment, or...