Type 1 Diabetes

Question 1

What is DM?

Answer 1

Chronic condition characterised by abnormally raised levels of blood glucose.

Question 2

Pathophysiology of T1DM

Answer 2

-Autoimmune disorder where the insulin-producing beta cells of the islets of Langerhans in the pancreas are destroyed by the immune system
=This results in an absolute deficiency of insulin resulting in raised glucose levels
=Patients tend to develop T1DM in childhood/early adult life and typically present unwell, possibly in diabetic ketoacidosis

Question 3

Symptoms and signs of T1DM

Answer 3

Weight loss
Polydipsia (thirst)
Polyuria (nocturia)
Blurred vision
Lethargy/ fatigue
Recurrent infections (thrush)
Poor wound healing

Question 4

How might T1DM patients present to hospital

Answer 4

-DKA
=abdominal pain
=vomiting
=reduced consciousness level
=polyuria
=polydipsia
=dehydration
=Kussmaul respiration (deep hyperventilation)
=Acetone-smelling breath (‘pear drops’ smell)

Question 5

Investigations of T1DM

Answer 5

-Blood glucose
=Finger-prick bedside glucose monitor
=One-off blood glucose (fasting or non-fasting)
=HbA1c (not as useful for patients with a possible or suspected diagnosis of T1DM as it may not accurately reflect a recent rapid rise in serum glucose)
=Glucose tolerance test (fasting blood glucose is taken after which a 75g glucose load is taken. After 2 hours a second blood glucose reading is then taken)

-Urine dip for glucose and ketones
-Fasting and random glucose
-C-peptide typically low
-Diabetes-specific autoantibodies

Question 6

What does HbA1c measure?

Answer 6

Amount of glycosylated haemoglobin and represents the average blood glucose over the past 2-3 months

Question 7

Diagnostic criteria for T1DM

Answer 7

-If the patient is symptomatic:
=fasting glucose greater than or equal to 7.0 mmol/l
=random glucose greater than or equal to 11.1 mmol/l (or after 75g oral glucose tolerance test)

-If the patient is asymptomatic the above criteria apply but must be demonstrated on two separate occasions.

Question 8

HbA1c criteria for diagnosis of T1DM

Answer 8

-HbA1c of greater than or equal to 6.5% (48 mmol/mol) is diagnostic of diabetes mellitus
-HbAlc value of less than 6.5% does not exclude diabetes (i.e. it is not as sensitive as fasting samples for detecting diabetes)
-In patients without symptoms, the test must be repeated to confirm the diagnosis
=It should be remembered that misleading HbA1c results can be caused by increased red cell turnover

Question 9

Diabetes-specific autoantibodies

Answer 9

-Anti-GAD (glutamic acid decarboxylase)= 80%
-ICA (Islet cell antibodies, against cytoplasmic proteins in beta cell)= 70-80%
-IAA (insulin autoantibodies)= 90% young, 60% older
-IA-2A (insulinoma-associated-2 autoantibodies)

Question 10

Clinical features of T1DM

Answer 10

-Typically <20 years onset, 40% >30yrs (age on onset below 50)
-Acute onset (hours-days)
-Recent weight loss typical (BMI below 25)
-Features of DKA (ketosis)
-Common ketonuria
-Personal and/or family history of autoimmune disease

Question 11

When should C-peptide and diabetes specific autoantibodies be tested?

Answer 11

-Type 1 diabetes is suspected but the clinical presentation includes some atypical features:
= age 50 years or above
=BMI of 25 kg/m² or above
=slow evolution of hyperglycaemia
=long prodrome

Question 12

Management of T1DM: HbA1c targets

Answer 12

-Should be monitored every 3-6 months
-Adults should have a target of HbA1c level of 48 mmol/mol (6.5%) or lower. Take into account
=person’s daily activities, aspirations, likelihood of complications, comorbidities, occupation and history of hypoglycaemia

Question 13

Management of T1DM: self-monitoring of blood glucose

Answer 13

-Recommend testing at least 4 times a day, including before each meal and before bed
-More frequent monitoring is recommended if frequency of hypoglycaemic episodes increases
=during periods of illness
=before, during and after sport
=when planning pregnancy, during pregnancy and while breastfeeding

Question 14

Blood glucose targets for T1DM

Answer 14

-5.5-7.5 mmol/l on waking (before breakfast)
-4.5-7.5 mmol/l before meals at other times of the day
-Less than 10mmol/L 2 hours after meals
-6.6-8.0mmol/L before bed

Question 15

Types of insulin for T1DM

Answer 15

-Offer multiple daily injection basal–bolus insulin regimens, rather than twice‑daily mixed insulin regimens, as the insulin injection regimen of choice for all adults

-Twice‑daily insulin detemir is the regime of choice. Once-daily insulin glargine or insulin detemir is an alternative

-Offer rapid‑acting insulin analogues injected before meals, rather than rapid‑acting soluble human or animal insulins, for mealtime insulin replacement for adults with type 1 diabetes

Question 16

Other drugs for T1DM

Answer 16

-Adding metformin if the BMI >= 25 kg/m²

Question 17

Risk factors that increase likelihood of T1DM

Answer 17

DRUGS
-Steroids
=Prednisolone / dexamethasone / hydrocortisone
-Atypical antipsychotics
=olanzapine (cannot articulate symptoms)
-Creon
-Alcohol

FAMILY
-Endocrine disease
=Thyroid/ Addison’s/ Coeliac/ Pernicious anaemia/ Vitelligo

PAST MEDICAL
-Impaired glucose tolerance
-Pancreas surgery/ alcohol excess/ pancreatitis
-Gestational diabetes
-Oncology
-Conditions requiring long-term steroid use

Question 18

Sick day rules

Answer 18

See picture

Question 19

Lipohypertrophy

Answer 19

-Rotate injection sites to avoid
=increases risk of hypos and unexplained highs
=every insulin injection will deliver a slightly different amount of insulin but variation greater with lipohypertrophy
-Insulin absorbed faster from abdomen so preferred site for quick acting (thighs for long acting)

Question 20

Why are overnight hypos a problem?

Answer 20

-Harder to detect than daytime hypos
-If frequent, can affect ability to detect hypos early
-Cause glucose to rise in the morning and after breakfast