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SPOT DIAGNOSIS
Which condition rings true ?
SIOBHAN is a 44-year-old who presents with itchy annular plaques on the abdomen , chest , neck , shoulders and back ( pictured ). These began several months ago as erythematous plaques on the abdomen , gradually increasing in number and expanding from the centre . Oral antihistamines , topical steroids and topical antifungals have had no effect . There is no clear contact precipitant and no recent medication use . Siobhan is usually well but has a strong family history of type 2 diabetes and , on recent routine blood testing , was found to have a newly elevated HbA1c of 7.4 %. Pathology was otherwise normal .
antibodies in all newly diagnosed T2D . 2
Progression to frank insulin deficiency is variable , and depends on the age at diagnosis , the presence of autoantibodies such as GAD , IA2 and ZnT8 , and the degree of antibody elevation . 2 The UK Prospective Diabetes Study found that , while 50 % of patients with LADA required insulin within six years of diagnosis , not all patients required insulin even after 10 years . 2
C-peptide , a marker of residual beta cell function , can guide the decision-making process for initiation of medication for LADA ( table 2 ). 2 A low C-peptide indicates insulinopenia , and initiation of insulin is recommended . Where insulin is not needed , some hypoglycaemic agents used for T2D may have a role in optimising glucose control in people with LADA . The aim of medical therapy is to optimise metabolic control and preserve beta cell function . 2
Many doctors are unfamiliar or lack confidence with the principles of medical nutrition therapy for diabetes . In 2019 , the American Diabetes Association ’ s consensus report on nutrition therapy for adults with diabetes noted that reducing carbohydrate intake has the most evidence for improving glycaemia , thus reducing HbA1c and the need for hypoglycaemic medication for people with T2D . 3 Likewise , limited studies of people with T1D have shown that LC eating patterns result in less glycaemic variability , more time in euglycaemia , less time in hypoglycaemia , and lower insulin requirements . 3 It is thus reasonable to consider the LC approach as part of the management options for people with LADA .
Several case reports document sustained “ honeymoon ” phase in adults of various ages with new diagnoses of T1D and positive pancreatic autoantibodies when they follow LC dietary and healthy lifestyle approaches . 4-6 Reducing the metabolic load in patients with newly diagnosed T1D and LADA may play a role in extending the honeymoon period . 4
Outcome
Jen has sustained a LC dietary approach since the diagnosis of LADA in 2019 . Her HbA1c has remained in the range of 5.2-5.7 %, while her autoantibodies remain elevated , especially the GAD . Her C-peptide has declined from 1.1 to 0.7 . During a period of intercurrent illness , an endocrinologist initiated small doses of insulin (< 5 units total daily ) to optimise blood glucose control . Jen and her GP continue to monitor her blood glucose , HbA1c and C-peptide while exploring other hypoglycaemics that may reduce insulin requirement .
Dr Kate Kelso is a GP and medical editor at Australian Doctor .
References on request from kate . kelso @ adg . com . au
Table 1 . Clues for LADA in the older person with newly diagnosed diabetes 1 , 2 1 . Classical symptoms of diabetes 2 . Absence of overweight or obesity , lower frequency of insulin resistance 3 . Aged under 50 at diagnosis 4 . Past history of autoimmune disease ( eg , thyroid autoimmune disease ) 5 . A family history of autoimmune disease
Table 2 . Recommendations for management of LADA according to C-peptide levels 2 C-peptide level ( normal : 0.4-1.5nmol / L )
Treatment approach < 0.3 A basal-bolus insulin regimen
0.3 – 0.7 Consider following the American Diabetes Association ( ADA ) algorithm for T2D ; avoid drugs that may deteriorate beta cell function ( ie , sulfonylureas ); modest evidence supports the use of other hypoglycaemic medications , such as metformin , GLP-1 RAs , DPP-4 inhibitors and SGLT2 inhibitors
> 0.7 ADA algorithm for T2D ; monitor with C-peptide levels
LADA may account for up to 12 % of adultonset diabetes .
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What is the most likely diagnosis ? a SLE b Tinea corporis c Generalised granuloma annulare d Sarcoidosis
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ANSWER The answer is C . Generalised granuloma annulare is a benign , non-infectious , granulomatous skin condition . The typical presentation is with skin-coloured-to-erythematous papules and annular plaques . The condition is considered generalised when at least 10 widespread annular plaques are present . Lesions may be solitary or coalesce , and the generalised form tends to be associated with pruritus . 1
The cause remains unclear , but a number of potential triggers have been reported , including drug exposure , viral infections , trauma and sun exposure . 2 Patients with diabetes are more likely to develop the condition . 1-4 Associations have also been reported with malignancy ; hyperlipidaemia ; rheumatoid arthritis ; and infectious diseases , such as HIV . 2-4
Diagnosis is typically clinical , with biopsy indicated for diagnostic uncertainty and histopathology usually revealing necrobiotic degeneration of dermal collagen surrounded by an inflammatory reaction . 4
Generalised granuloma annulare tends to be treatment resistant and may persist even with systemic therapies . Management of the underlying contributing causes or triggers may aid remission . Systemic therapies to consider include systemic steroids , isotretinoin , methotrexate , hydroxychloroquine , phototherapy and biologics . A step-wise approach to treatment escalation is recommended , weighing the potential benefits of treatments against the adverse effects . 1 , 4
In this case , the patient was treated with metformin , a low-carb dietary approach and oral hydroxychloroquine 400mg daily . Her HbA1c normalised within six months , by which time the lesions had begun to recede .
Dr Kate Kelso is a GP and medical editor at Australian Doctor .
References on request from kate . kelso @ adg . com . au
Image reproduced from BMJ 2022 ; 20 Jul , with permission from BMJ Publishing Group Ltd .